Thuso Mbedu is "petrified of heights" and admits there were times she wondered if she could back out of her role in The Woman King, in which she plays Nawi, a new recruit of the Agojie, an all-female unit of warriors that protected the African Kingdom of Dahomey in the 1800s.

And yet, the 31-year-old South African-born actress, who stars alongside Viola Davis and John Boyega in the film set to release September 16, insists on doing her own stunts — even when she's afraid or feels out of her element, she says. During intense physical training for the film, Mbedu found the motivation to keep going by reminding herself that the women of the Agojie really did what she was training to portray on the big screen. "This was someone's lived reality," Mbedu tells Shape. "This is what they did to protect their kingdom from their oppressors — to protect their people."

Of course, there were some differences between her training for the film and how members of the Agojie prepared for battle. For starters, her work began in Los Angeles with trainer and nutritionist Gabriela Mclain, who has a background in dance and martial arts. Before she even began strength training, Mbedu underwent a DNA health analysis, which provided information about her genetic predispositions, such as what foods her body easily processes, that allowed Mclain to customize a fitness and nutrition plan for the actress. Mbedu also underwent martial arts training, including Muay Thai; learned how to fight with weapons, such as bow staffs, swords, and machetes; and worked with a running coach to help her improve her sprinting ability.

Ahead, learn more about how Mbedu prepared for her physically intense role in The Woman King, what she likes to do for exercise when she's not training to play a warrior, and her strategies for getting out of a mental rut.

Playing Nawi was "one thousand and 10 percent" the most physically demanding role Mbedu has ever taken on, she admits. The actress began doing Muay Thai a minimum of three times a week, sometimes doubling up in the mornings and evenings when her schedule allowed. "I just wanted to work on my punching, on my reflexes, on my kicks," she says.

Then, once pre-production training officially began, Mbedu started strength training with Mclain, which involved working on agility, flexibility, and building muscle, she explains. Mclain was also involved in helping Mbedu fuel her body for her intense workouts. Based on a DNA analysis, "she stripped away a lot of things that would be counterproductive to what we would be doing when training, and she added [foods] that my body easily processes and works through," explains the actress. "She kept us on track, and I saw the difference in my body."

During this time, Mbedu was also fine-tuning her ability to believably wield weapons (her character's weapon of choice is the machete, but the actress's personal favorite was the bow staff). "I really enjoyed [safely] playing with the weapons [for training purposes] more than anything," she says. "It challenged the body and the brain in different ways."

She kept us on track, and I saw the difference in my body.

However, the most difficult element of training for Mbedu was running. "My goodness," she says, letting out an exasperated sigh when the topic arises. "That was a proper, proper challenge." Though, it was necessary. "My character, because of her size, relies more on her speed than anything," says Mbedu. In order to get through challenging running workouts, such as sprinting uphill, she called upon a unique source of inspiration: an anime character named Kenichi.

Around the time training began, Mbedu explains that she discovered the anime series Kenichi the Mightiest Disciple, which centers on a character that takes up martial arts to defend himself against bullies. "When I felt like giving up, when I was, like, really down and out, like really, really contemplating, 'Should I walk away from this project?' it took one day when my mind went 'What would Kenichi do?'" she explains. "And then after that, I did not look back."

When she's not learning how to fight with a machete or throw punches, Mbedu is likely doing a core workout she's found on YouTube. "My favorite type of exercise is anything that works my abs," she says. "I've always been, like, low-key obsessed with abs."

Although she has home gym equipment and enjoys following along with Bowflex workouts, Mbedu says she prefers specialized attention when it comes to exercising. "I suck if I do it by myself," she adds. "I won't even lie. I don't have the discipline to [work out] without a trainer." Luckily, she's been able to continue working with Mclain since wrapping up the filming for The Woman King. "Our relationship was so great, and she's so good at what she does," says Mbedu.

I'm always trying to challenge myself to try something new.

Outside of the gym, Mbedu enjoys "pushing the boundaries, little by little" by doing adventurous activities, such as indoor skydiving, ocean kayaking, and hiking. "I'm always trying to challenge myself to try something new," she says, explaining that her desire to do so stems from her aspiration to star in action films. "I don't want to get on a set and be afraid to try anything," she says.

When it comes to self care and mental health, Mbedu prioritizes rest above all else. "What I realized recently is…It's about the chaos in the mind, right?" she explains. "Allowing yourself to completely rest...emotionally, mentally, physically [helps calm the chaos]. But also talking. Finding someone who you trust, who you can talk to. And then, finding those things that you enjoy doing that will allow you to come back to the essence of who you are," she adds. "Those are my biggest things that usually get me out of my rut."

Mbedu also relies on a few activities she enjoys doing for herself when she has free time. These include journaling, taking care of her skin (she's a fan of Neostrata and Osea products), and getting deep tissue massages — during which she requests the "maximum level of hardness to ease the tension." But the one thing she becomes most animated about while discussing self care? Naps.

"Napping is self care for me," she says. "I put naps in my schedule because otherwise, everything feels overwhelming, and then I'm unproductive," explains Mbedu, noting that it's okay if she's unreachable for a little while. "I wake up and I'm, like, 'Good morning, again. Yes, I was napping. What's up? The world did not end.'"