Robert Pattinson's life mantra is "don't be a pu**y."

The 26-year-old actor - who is dating his Twilight Saga co-star Kristen Stewart - has always been really "scared" about his career but is trying to be more daring with his choices as he ages.

"[My life mantra is] don't be a pu**y. Basically, that's the best thing you can ever think. I've had so many occasions in my life where I've acted like a pu**y and regretted it. Have you seen that Mike Tyson documentary? That bit where he says he'd defeated the guy before he's walked into the ring, it's the same thing. With acting, I was always so scared. But you get to the point where you realize it doesn't matter."

The decision to be braver led him star as a billionaire playboy in new movie Cosmopolis, but he admits it is still a struggle for him to always feel completely comfortable: "Oh man, I was terrified on Cosmopolis. There was a sex scene and I was cringing. The girl was really comfortable with her clothes off - and I'm not. She took all her clothes off and I was just sitting there going, 'Um, I haven't got my 'ball-sack' on.' F**king amazing."