Sitting in a soundstage in Los Angeles, right outside the set of Captain Marvel, Samuel L Jackson pulls up a video on his phone and asks if we want to see “it,” almost like a proud father. He told us:

“A year ago, Brie started working out. And the girl that I did Kong and Unicorn Store with is not this person. She’s like 5 percent body fat now. She used to send me workout videos, which were like, crazy dope workout videos. The first one she sent me, she was lifting… like a hundred pounds. She was doing this thing with the waist-lift, about a hundred pounds. The last one she sent me was 350. She does chin-ups. And she sent me a video of her pushing a Jeep up a hill. It’s pretty amazing stuff.”

The homemade video shows a very muscular Brie Larson pushing a Jeep up a hill. It’s a video that her co-star sent to Jackson in confidence, showing her extreme training for her role in the Marvel movie. In the video, she makes pushing a jeep up a dirt hill look so easy, even though clearly none of the journalists gathered on set could attempt that feat of strength.

Jackson continued, “She’s made a distinct transformation that I don’t think a lot of people would be willing to do. It’s a huge commitment to do stuff like that. When I was doing Tarzan with Alexander, he would come to work at like four in the morning and go work out. Then he would eat, and then he would do his cardio, and then we would start to shoot. And every time they said Cut, somebody was putting a weight in his hand. He was doing curls, or he was doing push-ups. Brie’s sort of like that, at this point in her development, that she can actually do all of that stuff. It’s kind of crazy.”

Asked if Brie was trying to encourage Jackson to push it, Sam quickly responded “No, I have an age limit. I’m done with all of that. I go to Pilates. I only push my body weight. I don’t mess with any other weights.” He then pulled up another video where Brie is lifting weights with Aerosmith’s “Sweet Emotion” blaring in background of the gym. “Got it going on! Yeah, I’m impressed with what she’s doing.”

Later in the day, between takes, Larson sat down with us to talk about the film. Naturally, the first thing to come up was that jeep video.

Note: This interview was conducted in a press conference format with other assembled journalists.

Hey Brie, Sam showed us these crazy videos of you doing like-

Oh my gosh. He showed those to you too?

It’s his favorite thing.

I can’t believe it. I feel like close to 100 people that have come up to me and been like, “I saw this video that you sent Sam.” It’s so embarrassing. I sent that to him in private. He actually showed the person that was next to him on a plane too. Which I found out later. “Oh, I sat next to Sam who you sent that video and he showed it to me.” I was like, “Why?” I know, I know. He knows it was … I came from humble beginnings.

It wasn’t for you to push a Jeep up the hill.

It was a joke. It was a joke with the trainer, with my trainer, Jason Walsh, that I wanted to be able to … we were joking about it, that like, “Well, if I’m gonna go for it,” because I spent nine months training with him ahead of time, and I was getting super strong. And I was like, “Well, she can move planets, the least I could do is move a car.”

And so I thought it was gonna be, I’m trying to remember how long we had trained together for. Maybe five or six months at that point? And I just showed up in the gym one day and he was like, “All right, let’s do it.” And I pushed the car, yeah. And it wasn’t as hard as I thought, which was kind of crazy. There was someone in the front seat, in case for some reason, the car’s in neutral, but it’s going uphill. And I pushed it for a minute. Someone was in the car in case I like, crapped out, so it wouldn’t run me over. There was someone waiting there to put their foot on the brake.

And the driver makes it harder.

It does? Oh, because there was more weight. I didn’t get that. Totally didn’t think about that. It’s safe, don’t try it at home. Really don’t. It’s really probably not a safe thing to do, but it felt super satisfying, and I felt really crazy afterward. Because when you do stuff like that, I had never lifted weights or done things until this movie like that. So you get these crazy highs, and then you’re just kind of collapse onto the floor.

Is there a particular sequence or something that required such training? Or is it just a personal goal of yours?

No, it really all came out of ignorance, to be honest. I didn’t realize that you don’t actually do your own, most people don’t do their own stunts in these movies. I thought you did, and I’ve never been a particularly elegant or athletic person. I’m just an introvert with asthma and felt like I needed to be able to do that. I just thought, “I don’t wanna be on set, and they ask me to do things, and I don’t know how to do it.”

So I started training as soon as I could, which was right after I wrapped, so it basically started right as I wrapped picture, I locked picture on the film that I directed. I then went into that, which then turned into nine months of training. And nine months of just training-training, and three months of stunt training with the stunt team. We spent two hours every day, five days a week.

And it wasn’t until … everyone just went along with it, and was like, “Cool.” It wasn’t until we started shooting, and I started doing all my own wire work stunts, and flips and stuff that people were like, “You know nobody, now we’ll tell you, nobody actually does this. We just didn’t want you to stop. But now that you’ve kind of accomplished this thing, we don’t normally do this.” And I was like, huh?

But I love it. I mean it definitely makes things more complicated in certain ways, because I could be taking a lot more naps than I am. I could just be like, “Renee and Joanna got it, I’m gonna go eat some cake.” But instead it’s really become a huge part of how I learned more about her, and became her, and embodied her was through that, was through discovering my own strength. Pretty amazing thing.

Can you tell us a little bit about [Captain Marvel’s] personality? Especially in this scene, because she was being a little sassy, maybe she has a little bit of an ego to her. Is that how you look at it?

I mean, I think she has an ego, but in a healthy way. She doesn’t have an unrealistic expectation of herself, she just owns that she’s really good and really skilled. Which feels good to play. She also has an incredible sense of humor, makes fun of herself, makes fun of other people. Has no issue if someone makes fun of her.

So I will say that this character is probably the most dynamic character that I’ve ever played, there’s the most range. As of now, and we’ll see what the movie is, but as of now, it’s been the most range I’ve ever played in a character. From I’ve had to go through every emotion possible with her. And a lot of this movie, although it has great comedy in it, there’s also real depth to it and emotion. So I think that the film will have a lot. Which for me, that’s what I want. I wanna see complicated female characters. I wanna see myself, which is not a simple person. I surprise myself constantly by what’s happening and what’s coming up. So hopefully that’s what comes out on screen.

How has the part challenged you as an actress? Are there things where you found yourself, “Oh, this is really testing my limits.”?

Well, the general answer is just getting through a movie like this is a real challenge of everything. Of mind, body, and spirit. Because it’s a long one. And because I added in the physical side to it, it’s like doing a triathlon or something. So there are some days where I’m doing a fight sequence for three days, and then at the end of the third day, after I’ve been punching and kicking, then it’s like, “Okay, now we’re gonna do this one piece where you’re crying, and it’s emotional,” and you’re like, whoa. So it moves so fast, and there’s so much that at a certain point you have to sort of trust your instincts, and it’s been happening.