Green Lantern star Ryan Reynolds has admitted that he always fears taking on new and challenging movie roles.

The 36-year-old actor likes to play a variety of characters, but he explained that there is an uncertainty which comes with stretching himself as an actor.

He told Details magazine: ''There's ****-your-pants fear around every corner because I'm usually stepping out of a comfort zone that I haven't done before in a film. But that's the wonder of it, the beauty of it.''

Reynolds, who is married to Gossip Girl star Blake Lively, also admitted that he is extremely critical of his own work, but feels this self-reflection drives him to be a better actor.

''I can't say I've ever patted myself on the back and maybe that's what keeps me going, and that's a good thing," he said.

"It speaks volumes about how I perceive myself. Like a lot of people, I've got a self-loathing streak that's alive and well. It acts as a de facto engine when I'm working, but it also has its extraordinary pitfalls, too.''

When asked if he will continue his acting career well into his 90s, Reynolds replied: ''Do I really want to survive [to be 95]?

''Yeah, I think [I would like to keep working]. If it could be like the experience I'm having now and again, yes. I don't know what the outcome is, but I would love if it was meaningful in some way.''