(Cover) - EN Showbiz - Justin Timberlake says playing an action hero has always been a "boyhood fantasy".

The singer-turned-actor stars in new adventure movie In Time.

The film is based in the future where people stop ageing at 25-years-old. The plot follows Justin's character, Will Salas, on the run from a corrupt police force.

Justin was thrilled to be able to emulate some of his favourite childhood characters.

"This is not John Rambo," he told USA Today. "My character has his back against the wall, and he's street-smart. But there was a lot of boyhood fantasies here."

Justin's break out role was in Facebook drama The Social Network. Justin was excited to take on a physical role as his latest project.

"I wanted my character to move like he was light," he revealed. "All I can say is I lost a lot of body fat training for this movie."

The 30-year-old was so dedicated to the part that he even did a lot of his own stunts. A sequence which involved Justin scaling a banister caused him a serious calf injury.

However, Justin didn't let that get in the way of his performance.

"I felt like someone shot me in the leg, and it looks like in the scene I'm hobbling because I'm pulling [a hostage], but it's because I'm on one leg," he explained. "When they yelled 'cut' I actually fell down. But we got a great take out of it." (C) Cover Media