The actor revealed he had never boxed before taking on the role as he spoke to INSIDE EDITION at the New York City premiere of the movie.
Jake Gyllenhaal has revealed he had never boxed before his leading role in boxing flick Southpaw - so the role meant some seriously hard work.
Speaking to INSIDE EDITION at the New York premiere of the movie, the actor described his gruelling training regime as he prepared for the role of Billy "The Great" Hope.
"It was actually a really interesting process because I didn't know how to box at all," he said.
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"I was just terrified and I figured I needed to learn how to do it. I spent twice a day for five months - I figured if I spent twice a day [boxing] for five months, then 10 months.
"I would've done it three times a day if I had to. I was just basically scared."
But he didn't just work hard in the gym.
"I just gave myself to it in every way I could," he said. "Watched so much tape on so many fights in the history of fighting."
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He was joined at the premiere by Rachel McAdams, who plays his wife in the film. She too learned to box for the role.
"It's a great workout," she said.
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