Brie Larson | Train Like a Celeb

To be the first-ever female superhero to headline a Marvel movie , you have to be something special. Thankfully for comic book fans (and the members of the MCU left in limbo after the events of Avengers: Infinity War), Captain Marvel, as portrayed by Academy Award-winning actress Brie Larson, has more than enough power to lead her own 1990s-set film—then (potentially) save the universe from Thanos' plans in the final film of the MCU's current phase. Larson has the bonafides to play just about any role she'd want as an actress, but the physical demands of portraying a superhero gave the 29-year-old star a new type of challenge. Larson admitted that she wasn't much for the gym before shooting the film—but that all changed as she trained for the role. “I just wanted to be a brain, so I’ve only cared about reading books and understanding words, and anything that involved my body made me itchy,” she told E! News . “But this was an opportunity for me to … make my body mine.” Larson worked with LA-based trainer Jason Walsh, who counts Matt Damon, Miles Teller, and John Krasinski as past clients, to get in superhero shape. "Brie came to me, and the good thing was we had 9 months," Walsh told Men's Health when we stopped by his gym. "Her character is very very physical, so we needed her to be super resilient, super strong, so that she can recover from this and not risk shutting down production." To demonstrate how he helped Larson transform from a cerebral actress into a proud Instagram fitness maven and believable superhero, Walsh walked us through one of their typical training sessions, which calls for a progressive overload to help break through plateaus. "Brie worked out 5 days a week with me pretty much the whole nine months," says Walsh, before giving Larson the highest praise a trainer can bestow upon a client. "She worked her ass off to get into shape for this movie."