Find out how Brie Larson whipped herself into superhero shape to play Captain Marvel

Brie Larson is proud of the work she put in to become superhero strong for her starring role in Captain Marvel.

Just three years after winning an Oscar for Room, the actress, 29, is making history playing the first female superhero to lead a Marvel movie — a job that she took seriously and completely transformed how she thinks about her personal strength.

“I carved out nine months, and was like ‘I’m going to hit it as hard as I can and see how far I could go,'” Larson tells PEOPLE in the latest issue. “I was able to get way further than I ever thought I would ever get to in my life. I never thought I’d be able to deadlift 225 lbs, never thought I could hip thrust 400 lbs, I didn’t even know hip thrust existed before and so that was great.”

Larson also added martial arts to her training regimen, which she is still practicing today.

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Brie Larson pushing a Jeep during training
| Credit: Brie Larson/Instagram

For much more on Brie Larson and Captain Marvel, pick up the latest issue of PEOPLE on newsstands Friday

“The martial arts, the boxing, all of that added a new element that’s really stuck with me that I can’t wait to spend the rest of my life continuing to study,” she says. “Because I love the space my brain gets into when I’m doing it, it’s like a meditation, it really sticks with me and it’s profoundly changed the way I live my life.”

She says that her strength training has also changed her posture and how she carries her body everyday.

“It does change [your posture] because your back gets stronger, especially Judo. Judo uses tons of back muscles,” Larson explains. “You get super sore and you end up getting super strong again and you feel more capable at least I did.”

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Brie Larson as Captain Marvel
| Credit: Marvel Studios

When asked if she ever thought she would end up in a superhero movie, Larson recalls an early childhood dream of playing another beloved and badass leading lady.

“I wanted to be Princess Leia,” says Larson. “I had a shirt that was way too big for me that I held onto forever. I was convinced they were going to do a movie where they would need a young Princess Leia, and I was going to audition for it, and that was the shirt I was going to wear!”

Captain Marvel opens in theaters March 8.