This video is part of Health's My Mantra series. Follow along with new videos on our Instagram page and share your own words of wisdom using #MantraMonday.

Sarah Michelle Gellar knows what it means to be motivated. The actress become a household name in the 1990s when she landed a starring role in Buffy the Vampire Slayer, and she's continued to steadily work in TV and film since.

With a busy career and parenting duties to handle, it's no surprise that she relies on a killer mantra to keep her going. Gellar tells Health why her mantra works for her (check out the video above!), and why she continues to harness its power.

RELATED: Sarah Michelle Gellar Reveals Postpartum Depression Struggle in Health Care Plea

"There was a quote from the musical Chess, the original production, that always stuck with me: ‘You taught me baby, how the few who win acquire, it ain’t practice, it ain’t skill, they’ll help, but not as much as wanting will.’ And I think for me, it encompasses everything, which is that you have to really want something in life to make it happen," explains Gellar.

"It’s not about waiting for something to come to you," she continues. "That if there is something you’re looking to do, something you’re looking to experience, those are moments you need to make happen for yourself."

Honestly, I think I probably use it every day, I remind myself I want to be better. To accomplish different things. To want to be more patient. Whatever those moments are, for me it’s about just keep it at the back of my head," she adds.

RELATED: Sarah Michelle Gellar on Shannen Doherty's Inspiring Breast Cancer Battle: 'That's What Real Bravery Is'

This is the first time Gellar has touched on her personal life. In 2017, the actress opened up about her battle with postpartum depression in an emotional Instagram post, explaining how the disease impacted her daily life. 

“Having kids is wonderful, and life changing, and rarely what you’re prepared for,” Gellar wrote at the time. “I love my children more than anything in the world. But like a lot of women, I too struggled with postpartum depression after my first baby was born.”

“I got help, and made it through, and every day since has been the best gift I could ever have asked for," she wrote. "To those of you going through this, know that you’re not alone and that it really does get better."

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Bad guys, take note: Here’s even more proof you need to be careful who you mess with—and it comes in the form of an 82-year-old bodybuilder.

Willie Murphy, a grandmother who lives in Rochester, New York, recently found herself in danger when an intruder broke into her home. However, instead of leaving with jewelry and money, the criminal left in handcuffs— and with injuries—because he happened to break into the home of an award-winning former bodybuilder.

According to Murphy, she was getting ready for bed Thursday night, after 11 p.m., when she heard a man pounding on her door. “He was outside and saying, ‘Please call an ambulance,’ saying, ‘I’m sick, I’m sick,’” she told WHAM-TV.

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She called the police, refusing to let him inside. Apparently, he got angry and forced his way into her home. “I hear a loud noise,” she said. “I’m thinking, 'What the heck was that? The young man is in my home. He broke the door.”

Instead of allowing herself to be the victim of a crime, Murphy, who works out at the local YMCA almost every day and can lift 225 pounds, fought back.

Because it was dark, she was able to hide while the intruder walked around the house. She grabbed the closest thing she could find—a table— and started attacking him. Once the table broke, she started whacking him with the metal legs.

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“It's kind of semi-dark and I'm alone, and I'm old,” she said, explaining the situation. “But guess what, I'm tough; he picked the wrong house to break into.”

Murphy didn’t stop there. Once he was injured, she ran and grabbed a bottle of shampoo, pouring the entire bottle on him. Then, she finished him off with a broom.

When the officers arrived, the man could barely move, and was sent to the hospital. Murphy believes he was “relieved” to be on his way.

The first responders were quite impressed with her self-defense skills— and rightfully so. “The officers that came wanted to go on my front porch and take selfies with me,” she said.

Murphy, who is not pressing charges, hopes that her story inspires people of all ages.

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Instagram-famous personal trainer (and all-around badass) Kayla Itsines had a baby girl in April—but from the day she announced she was pregnant, Itsines was very vocal about her journey to motherhood and all it entailed (like how she struggled with morning sickness and restless leg syndrome while pregnant.)

Now, Itsines is opening up about one of the more difficult parts of her postpartum journey: Hitting the gym for the first time after her caesarian section—just six weeks after her daughter, Arna Leia Pearce, was born.

Itsines, a lifelong athlete, was eager to get back to working out after she gave birth. She tells Health, “My first session back at the gym, I went onto the treadmill, and I was like, ‘Alright, cool. I’m going to do a fast walk because they told me I could walk.’” 

But that fast walk didn't go entirely as planned. “I stupidly put the treadmill up to a fast walk speed that I used to be able to do. The treadmill started going. I started to feel this weird, odd pain on my right side," she says. "The treadmill pick[ed] up pace quite quickly. I started to panic; I couldn’t turn the treadmill down fast enough.”

Itsines wasn’t able to spread her legs to the sides of the treadmill so she could get off the moving track, and she grew worried she would face plant on the moving belt. Luckily, it slowed down in time for her to regain control, but that incident made her realize just how much her body had changed since she had a baby. That day she ended up walking slow for about 13 minutes. “Then I had to get off,” says Itsines.

RELATED: Kayla Itsines Dishes on Her Fave Foods and More

The realization that she wasn’t as fit as she’d like to be was a tough one. “It was a struggle, really hard. I just remember being so upset and devastated that I wasn’t able to complete [a workout],” says Itsines. That struggle is what led to her new post-pregnancy workout program, to help women who have just given birth figure out how to get back in shape in a safe way. The workouts featured in the program, which include strength-training exercises and low-intensity steady state (LISS) cardio, are 15 to 25 minutes long, and the program lasts 16 weeks.

Itsines says that one thing that made this part of her journey especially difficult was that she didn’t know what it felt like to be out of shape. “It’s different for a person who has, maybe, never worked out before," says Itsines. “For me, I don’t remember not being fit. So I was super confused.”

Itsines stressed the importance of listening to your body when you return to the gym after giving birth, explaining that this is not the time to test your limits. “If I could give advice to women, it’d be not to push them to go straight back into fitness. Not to put that pressure on them…

Her solution? Quick 20-minute circuit routine, which she shared on her Instagram page Wednesday night. "On good days, workout. On bad days, workout harder,” she captioned the of herself crushing at what looks like her home gym. “Today’s circuit is what I do when I just have 20 minutes with @lauralizkeller [Sims' personal trainer] to get it in and still break a sweat!”

RELATED: Halle Berry Shares Photo of 6-Pack Abs on Instagram—and Her Fans are Freaking Out

Sims' entire workout is made up of seven moves, according to her instagram—and in seven different slides, she shows herself demonstrating them. Here's what her 20-minute circuit workout looks like, doing each move for 45 seconds, and repeating the circuit two to three times:

Jumping jacks
Modified pushups
Tricep dips
Squat jumps
Leg raises
Burpees
Lateral bend and hold (squeezing abs)

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But Sims doesn't stop there—throughout the entire workout, she wrote that she ankle and wrist weights, though she doesn't say exactly how heavy. In her caption, Simms also called out athleisure brand Nylora, who makes her (super-cute) workout set.

As far a Sims' workout routine goes, it's actually really smart to do circuit training when you’re pressed for time, says Albert Matheny, RD, CSCS, of SoHo Strength Lab and Promix Nutrition. “If your goal is to burn calories and wear yourself out during a workout, circuit training is a really efficient way to do that,” he says. Circuit training is also great because it allows you to move on to work other body parts when one area gets fatigued, he says.  “As you’re resting one muscle group, you can start working another group,” Matheny says.

While Matheny says you can “make a circuit training workout out of anything,” he says it’s ultimately best to transition from focusing on one area of your body to another to give certain body parts time to recover in between—and to help you ultimately go harder. “Go from lower body to upper body to total body exercises,” Matheny advises. “It’s really efficient.”  Yup, even if you only have 20 minutes, like Sims. 

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I couldn’t sit by as their futures were threatened by this silent health crisis. And so, I started taking girls hiking on Saturdays. Each time, we walked and talked about things that might be a barrier to them living their healthiest lives. At the same time, my best friend, Vanessa Garrison, was grappling with women in her family dying too early. I knew we had to do something bolder and more transformative.

Read more stories about innovative and inspirational women, check out our Wellness Warriors series 

Vanessa and I set an audacious goal to get 1 million women to walk—to improve their own health, to create a new culture of health for their families, to inspire their daughters, and to take back their neighborhoods. We invited 532 friends on our combined email lists to walk with us.

Walking is the single most powerful thing you can do for your health. Walking 30 minutes a day, five days a week reduces most chronic disease by half. Each time we walk, we also combat loneliness and isolation, and build community, friendship, and culture.

RELATED: Your Walking Speed Can Tell You How Fast You're Aging

This is how GirlTrek was born. And not only do we organize walks but we also audit the needs of our neighborhoods as we walk. “Oh, we could put a garden there.” “There really needs to be a traffic stop here.” Or: “This mother has lost her son. Let’s walk and talk with her while she grieves.”

The more we walked, the more word spread. Today, with more than 270,000 members, we’re one of the largest public health nonprofits for African American women and girls in the U.S., and we aspire to reach 1 million members in the near future.

RELATED: These Are the Best Walking Workouts, According to Fitness Experts

When we are asked who’s in GirlTrek, we say: It’s rowdy college students, it’s the lunch lady, it’s all the women on the church pew—it’s everybody working together.

Our national team walked 100 miles on parts of the Underground Railroad, inspired by the footsteps of Harriet Tubman. But I find it rewarding when women have their own quiet breakthroughs, like a woman who’s gotten up and walked by herself every single morning for a year, and on the 365th day, she tweets about it.

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As a mom of two, I’d gained weight with both of my pregnancies and never really lost it. So in 2014, a couple of close friends told me over a glass of wine, “You need to take more time to get healthy.” 

The message sunk in. I started making better food choices and running. Over the course of 10 months, I lost 35 pounds. I don’t care much about fashion, so I kept wearing my old clothes until the summer of 2015, when my husband told me one day, “You can’t go to a business meeting in that bra.”

Read more stories about innovative and inspirational women, check out our Wellness Warriors series

It didn’t fit me around the torso anymore, and I couldn’t tighten it. While buying new bras at a local store, I asked the clerk what I could do with all of my perfectly good used bras that no longer fit me. She looked at me and said, “Homeless women need bras.”

Those four simple words changed my life. I went home and called a shelter near my home in the Washington, D.C., metro area. Their response: “How soon can you bring them?”

RELATED: This Bra Is So Comfortable, It’s Sold Out 10 Times

I don’t normally post on Facebook, but I felt compelled to mention that I’d just learned of this overwhelming need. Did anyone else have old bras to give away? The shelter had mentioned that women and girls are also frequently in need of pads and tampons, so I asked for donations of those, too.

People shared, and reshared, my request, and it got crazy really fast, in a “lightning in a bottle” way. Within two days, my Facebook group, Support the Girls, was born. A few months later, my husband made a website to keep up with the demand.

RELATED: This Insanely Comfortable Bra Has Over 2,600 Near-Perfect Reviews on Nordstrom

By that time, I’d made it to the shelter, and I had collected more than 1,000 bras and more than 7,100 pads and tampons. It didn’t make sense to stop there. Today, Support the Girls has nearly 60 affiliates across the U.S., as well as around the world. We’ve donated around 5 million products, including mastectomy bras, prosthetics for women going through cancer treatment, binders for trans boys and men, menstrual underwear, and menstrual cups. We’ve donated to Chicago public schools and the Indiana Department of Corrections, and provided supplies during and after natural disasters like Hurricanes Harvey, Irma, and Dorian.

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Daphne Oz, author and TV host of Master Chef Junior, shared a super-relatable selfie on Monday, to show that she’s jumping back into the fitness game after giving birth just 10 weeks ago.

“Everyone starts somewhere,” she wrote, along with the hashtag #10weekspostpartum. “Just got sweaty and it felt so GOOD!!”

Oz, 33, who’s the daughter of TV personality Dr. Mehmet Oz, gave birth to her fourth child in August, according to People. She welcomed daughter Giovanna Ines Jovanovic (nicknamed Gigi) with husband John Jovanovic.

This was Oz’s fourth pregnancy in five years—Daphne has three other children, Philomena, 5, Jovan, 3, and Domenica, 1, with her husband—and she told People it was the most physically challenging. Oz said that she battled the challenges that came with her pregnancy by “trying to feel good in my skin, whether it’s finding little ways to take care of myself or finding clothes that fit in a way that makes me feel good.”

RELATED: 3 Meal Prep Hacks Daphne Oz Swears By

As far as her workout Monday, Oz said it was actually her second since giving birth to Gigi—and that she’s in no hurry to get back to working out on the regular. “I’m not in a rush,” she wrote. “I just want to start to feel my core again and strength in my skin. Consistency and baby steps get it done #onmyway #herewego.”

Also important: The new mom chose a super cute workout set from Outdoor Voices for her sweat session. The Athena Crop Top ($45; outdoorvoices.com) offers more coverage while still showing off your core, and the coordinating Hi-Rise 7/8 Warmup Leggings ($75; outdoorvoices.com) keep you comfortable and stay in place throughout your workout, thanks to the stretchy yet compressive fabric.

Of course, this isn’t the first time Oz has gotten real with her Instagram followers about postpartum life. Last year she posted a photo of herself seven weeks after giving birth. She encouraged new moms not to get discouraged with the challenges that come with motherhood and countered the advice that women should simply “bounce back” after giving birth. “There is no bounce-back, it’s all onwards and upwards,” Oz wrote.

In addition to her body positivity, Oz has also shown a few of her workouts on Instagram, pre-pregnancy. In December 2018, she shared a photo after “starting the weekend sweaty” with a class by Obé Fitness, with instructor Madelaine O’Connell. Before that, Oz shared another sweaty selfie after a workout class, where she revealed she sweats “(almost) every day.” According to Oz, her workouts aren’t about immediate results, but rather doing something good for yourself every day. Amen to that.

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Another week, another Britney Spears workout video—and this time the pop star is combining two of her favorite routines.

In a new Instagram post, shared Monday, Spears shared a video of herself doing an exercise mash-up. "My normal yoga and weights routine always gets me going!!!!!" she wrote. "Great day !!!!!!!"

During the sped-up video, Spears, 37, is shown wearing pink polka-dotted bootie shorts and a black strappy sports bra. Throughout the video, you can see Spears going through a yoga flow (from Downward-Facing Dog to Upward-Facing Dog) and doing other yoga poses like Child's Pose and Cobra Pose, along with variations on free-weight lifts. 

RELATED: Britney Spears Shows Off Her Abs While Doing the Splits to Share Her New Workout Routine

Of course, Spears is no stranger to sharing her workouts on Instagram. Just last week, she shared a video of herself with an unidentified stranger doing an acro yoga-esque routine together. In the video's caption, Spears wrote that it was her "first time to walk on my hands up and down stairs," which, of course, she shared a video of. In addition to her handstand walking, Spears was also shown doing backbends and balancing on her partner's feet. 

RELATED: Britney Spears' Boyfriend Sam Asghari on How He Lost 100 Lbs. — and the Couple's Fun Workouts

But yoga and free weights aren't the only workouts Spears does. In another recent Instagram post, Spears shared that she had just logged some pool time. "Yes I did my challenge of 60 laps and yes it was hard !!!!!" she wrote. (Spears, however, spoke to her viewers and said she typically swims 20 laps a day—she just chose to challenge herself that particular morning). "When I swim laps in the mornings …. I usually have to take a nap … the water makes me sleepy like a baby," she added.

Clearly, Spears knows a thing or two about switching up her workouts to keep herself engaged. So what's next, Brit? Maybe some HIIT workouts?

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Jada Pinkett Smith is showing fans that you don’t need a fancy gym membership to get in a decent workout.

On Tuesday, the 47-year-old Girls Trip star shared a video of the intense full-body exercise routine, created and demonstrated by her trainer Jeanette Jenkins all done in a hallway at the W Hollywood without the aid of a single piece of gym equipment.

Dressed in a black athleisure ensemble with a hot pink sports bra and matching Nike sneakers, Jenkins appeared cool as a cucumber throughout—even though she was upside down for most of the workout.

“THIS!!! Whooped my a#@!!!” Pinkett Smith captioned the video, set to Migos’ song “Stir Fry.”

“Try it! It’s a GREAT routine and u don’t need a gym!” she added.

RELATED: Jada Pinkett Smith Admits She's 'Not Built for a Conventional Marriage': It Would 'Kill Me'

Jenkins, a Los Angeles-based trainer dubbed it the “7 Exercise Core & #WallWorkoutChallenge“—going into detail about it on Instagram. 

RELATED: The 17 Best Butt Workouts from Kelsey Wells, Jeanette Jenkins and More Fitness Stars

To follow along, one must repeat three sets of wall mountain climbers, toe taps, walk out and ins, alternating knee crosses, hand to opposite knees, walk planks to squat jumps, and single leg wall jumps, for 30 to 60 seconds each.

“Let’s just say my entire core & upper body were sore for three days after this!” the trainer wrote in her own IG post. “You can do it! Have fun!!!!”

Of course, fans of Pinkett Smith’s know this isn’t the first time she’s shown off her workouts on Instagram.

Late last month, the wife of Will Smith flaunted her impressive set of abs alongside 17-year-old daughter, Willow, and mother, Adrienne Banfield-Jones, 64, after their family workout.

RELATED: The Best Booty-Boosting Exercises, According to Jeanette Jenkins

“That three generational thing,” Pinkett Smith captioned the shot of her and her family. The three ladies are nearly matching in their sports bras and black leggings, while baring their fit stomachs.

In August, Smith posted a video of Banfield-Jones breaking a sweat during a gym workout. “Why is Gam Bam putting me to shame???” Pinkett Smith joked.

Banfield-Jones also previously showed off her abs on her own Instagram in May, when she posted a revealing shot of herself in a colorful bikini.

RELATED: Jada Pinkett Smith Just Revealed She’s Struggled With Sex Addiction—Here’s What That Means

The three generations of women are tight-knit, and launched their own Facebook talk show, Red Table Talk, where they share captivating personal stories.

“I feel like the only real valuable thing in life is sharing what we’ve gone through…