Watch Jake Gyllenhaal Get Super Buff for 'Southpaw'

Jake Gyllenhaal transformed his body for his upcoming boxing movie Southpaw, and we have a look at the actor's intense training regimen.

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"I knew nothing about boxing when I started really," Gyllenhaal in the clip. "I knew that in order for me to pull it off in any way, I was just going to have to learn how to do it. When I set my mind to something I just won't stop until I do it. It's something I pride myself on. It's something I hate about myself. By the end I felt like I could do it."

Gyllenhaal fully committed, gaining 15 pounds of muscle for the role.

The movie follows fictional Junior Middleweight champ Billy Hope (Gyllenhaal) as he fights his way to a championship belt only to lose everything.

Rachel McAdams stars as Billy's caring wife Maureen, who is gunned down in front of him by another fighter wanting a shot at Billy's belt. Maureen's death sends Billy into a self-destructive, drug-addled spiral that leads the courts to take away his daughter (Oona Laurence). Making matters worse, Billy's income gets cut off after a doping scandal forces officials to suspend his boxing license for a year.

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Left with nothing, Billy turns to former boxer Titus "Tick" Wills (Forest Whitaker) to rebuild him into the champ he once was and defeat the man responsible for his wife's death.

Southpaw opens July 24.