To portray a female boxer, Hilary Swank had to not only learn how to box, but mold her body into the guise of someone who has probably spent her whole life training. Swank had about 90 days to do it.

"My training was two and a half hours of boxing and approximately an hour and a half to two hours lifting weights every day, six days a week," Swank said. "The producers asked me to gain 10 pounds of muscle. I gained 19 pounds of muscle. I started at 110 and went to 129. And in order to do that, I had to eat 210 grams of protein a day. Now, your body can only assimilate so much protein, so I had to eat every hour and a half. So with a meal, I would drink my egg whites because I could never eat 8 to 12 egg whites in a sitting. It's just the worst thing ever. I had to drink flax oil. Flax is a really important oil for your brain and to also just keep everything moving when you're eating that much protein. It's a really important fat. Like one tablespoon of Flax oil has like 15 grams of fat in it."

Even her sleep was coordinated into her daily regimen. "The thing was, I needed nine hours of sleep a night because your muscles have to be able to rest in order to build or you actually reverse yourself. So I slept nine hours a night but I had to wake up in the night and drink protein shakes because I couldn't go that long without eating."