Woody Harrelson's film roles get him in a "weird" mind set.

The 'Messenger' actor - who plays the role of a soldier who struggles with an ethical dilemma when he becomes involved with a widow of a fallen officer - admitted the extreme role had really affected him because it made him truly understand the experiences of a soldier.

He said: "These roles get me into a weird state of mind. The role in 'The Messenger' really got to me. For the first time I realised what soldiers go through. What they do is moving and I support them. However, at the same time I'm absolutely against the Iraq war. You have to distinguish between that."

The 48-year-old star also claimed he doesn't care about success because it is more important to take on parts which he had a "belief" in.

He added in an interview with Germany's GQ magazine: "Maybe the fact that I only take on roles I completely believe in. There are people in Hollywood who would kill their grandmother if it helped their career. I'm not interested in being successful, though."