How will Charlie Hunnam get in shape for the role of Christian Grey? The 33-year-old actor is already in fantastic shape but according to mnn.com, his intense workout for the movie could include martial arts.

The "Sons of Anarchy" star already has experience practicing martial arts and is constantly in the gym. It's not clear if he will have a trainer and honestly he might not need one. Hunnam revealed to Men's Fitness that he is obsessed with working out but doesn't hit the gym to necessarily look good.

"The benefit of working out is 90 percent mental and 10 percent physical," Hunnam said. "I feel better - like I have more energy. But the mental side is an extraordinary benefit. I'm happier, more confident, and more positive when I work out. And I feel like I'm a better actor because of the clarity it gives me."

In the book, Christian Grey was also into working out. Granted it was for a slightly naughtier reason - he wanted to make sure Anastasia Steele could physically keep up with his demands - but it's nice to know Hunnam is physically capable of playing the tall, muscular, broad-shouldered billionaire.

Despite how busy and hectic his schedule is the actor told GQ that he always finds the time to get to the gym.

 "I work 15 hours a day and still go to the gym," he said. "Most people work eight hours a day and say 'I haven't got time to work out.' Bullshit! If you want to be super-fit and look ripped then you find the time no matter what."

He also credits his chiseled abs to a clean diet - he drinks vegetable juice everyday - and natural foods. Most recently he has taken up Bartendaz, an intense fitness regime created by a group of guys from Harlem and Brooklyn that combines calisthenics, military drills and martial arts. The workout is usually performed at parks and playgrounds (check out a video here).

"Working out in the gym, doing the same stuff day in and day out can get boring," he said. "What keeps it fresh and fun is freestyling moves. I got to the point where I could do three muscle-ups then start adding the flips in between and creating signature stuff."

What do you think about Charlie Hunnam's workout? Is he ready to play Christian Grey?