Scarlett Johansson revealed that she "had never stepped foot in a gym" before undergoing rigorous training for her role in Iron Man 2.

The actress, 37, made her debut as Natasha Romanoff/Black Widow in Iron Man 2, which the actor described in a recent interview with Vanity Fair as "a humongous moment."

But despite being one of Hollywood's most successful actresses, Johansson claims she's actually not like most of the other A-listers who spend their days working out in the gym.

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"Because I was, I don't know, 23 or 24 when I was cast in 'Iron Man 2.' I had never stepped foot in a gym, and I had five weeks to prepare myself for these huge stunt sequences," she said.

"Back then when we were doing it, over a decade ago, it was before we kind of figured out how to be most efficient in the process of shooting stunt work – what could be handed off to other stunt people and what the actor would practically need to know."

"So I was doing these huge choreographed sequences and I had no previous experience with any of that stuff," she went on. "It was just a massive lifestyle change immediately upon getting cast."

"I was living in LA at the time, and I went to this massive, huge, muscle meathead gym. I didn't know how to use any of the equipment. I mean, I was so intimidated."

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Johansson previously reflected on the hit film in June last year, telling HelloBeautiful that her character was initially "so sexualized."

She told the outlet: "[She's] really talked about like she's a piece of something, like a possession or a thing or whatever - like a piece of a**, really. And Tony even refers to her as something like that at one point."

Johansson said she was appreciative of the changing attitudes towards girls in Marvel films.

"Now people, young girls, are getting a much more positive message," she said. "It's been incredible to be a part of that shift and be able to come out the other side and be a part of that old story, but also progress; evolve. I think it's pretty cool."

Featured image credit: REUTERS / Alamy

Scarlett Johansson says she'd 'never stepped foot in a gym' before appearing in 'Iron Man 2'