Brie Larson learned to be a ''diligent secret-keeper'' when working on 'Avengers: Endgame'.

The 29-year-old actress - who plays Carol Danvers, also known as Captain Marvel, in the superhero franchise - says she had to mentally ''delete'' the plot line of the movie to avoid spoiling it for the fans and even refused to tell her family.

She told USA Today: ''I just never wanted to feel like I was going to slip up or that I was going to say the wrong thing. I was like, 'I can't live with myself being the one that spoils something.' So I really just deleted it. I tried my best to journal it if I want to recall it and go, 'Oh yeah, that was a crazy time.' And I'm excited when the movie comes out to finally be able to talk about it and go, 'Yes, this was crazy.' But my family doesn't know. I haven't talked to anybody about anything because I'm just a very diligent secret-keeper.''

Meanwhile, Brie previously revealed she did ''nine months'' of training for 'Captain Marvel'.

She shared: ''I did nine months of just training, training, and three months of stunt training with the stunt team where we spent two hours every day, five days a week. It wasn't until we started shooting and I started doing all my own wirework, stunts and flips and stuff that people were like, 'You know, nobody... now we'll tell you; nobody actually does this.' I was like, 'Huh.' But I love it. It definitely makes things more complicated in certain ways because I can be taking a lot more naps than I am.''