Robert Pattinson constantly expects failure.

The 'Cosmopolis' star- who was recently left devastated when girlfriend Kristen Stewart confessed to an affair with married director Rupert Sanders - thinks it is important never to feel ''validated'' by his performances and instead always tries to be pessimistic about his career in order to be a better actor,

He said: ''I think as soon as you feel validated, you're a bad actor. You have to constantly feel that there's a 99 per cent chance of failure. Total failure. Devastating failure.

''You should feel like every single job is the potential where you're never going to get another job again. Not in a bad way - you should feel good about it, because then you're in it. It's all about living in the present.''

The 'Twilight Saga' star admitted being cast in 'Cosmopolis' was one of the first times he felt ''like an actor''.

He added on 'MTV First Robert Pattinson': ''[The casting was] one of the first times I considered myself an actor.

''I had to come to terms with that. That was one of my first questions. 'What do you see in me? Why? Why? Why are you hiring me?' [Director David] Cronenberg is one of those people when you're asked who you want to work with, he doesn't even come into my head. Because that's like saying, 'Want to work with Orson Welles?'

''It was total luck. It was like a gift to get the job. I sort of fell into acting. It's not like I've been striving since I was a kid to get this. But I like movies more than acting, I think. I like the idea of being in movies that I like, contributing something.''