The 50-year-old star first realised he was getting older when he watched his 2009 film 'Up in the Air' back, and was confronted with his aging self.
He told Total Film magazine: "It's interesting to watch yourself grow older on screen. I watched 'Up in the Air' and thought, 'who's that old, grey haired guy?' It was me. I never wear make-up for movies. It's starting to show."
George added the film was one of his best times on set and the end results were some of the best of his career, but marked out an incident while filming 1999 movie 'Three Kings', directed by David O. Russell, as "the worst" experience he has ever had.
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He explained: "Once he went after a camera car driver who I went to high school with. I had nothing to do with his getting his job, but David began yelling and screaming at him and embarrassing him in front of everyone on set.
"I told him, 'You can yell and scream and even fire him, but what you can't do is humiliate him in front of all these people. Not on my set, if I have any say about it.
"Another time he screamed so much at a script supervisor that he made her cry. It was truly, without exception, the worst experience of my life."