The actor was 29 and at the cusp of major stardom but such was his problem that he once ended up in hospital after smashing his head during a party, reported People magazine quoting GQ.
"If I continued it, I was really going to sabotage my whole life," the 'American Hustle star' said. Cooper, now 38, says he was never late to the set, but "of course it hindered the work."
"I was doing these movies, and I got to meet Sandra Bullock (his costar in 2009's 'All About Steve') and meet these people and work with them. And I'm sober, and I'm like, 'Oh, I'm actually myself.
And I don't have to put on this air to be somebody else... I was rediscovering myself in this workplace, and it was wonderful," the 'Hangover' star said.