|Butler went to rehab for prescription drug addiction|
Even though he believes if he had more willpower he wouldn't have needed specialist treatment, Gerard admits the experience has made him a better person.
He said: "Maybe a stronger person wouldn't have needed to go. When you hear the word rehab, you think, 'He's a mess, he's f***ed up.' But I'm glad I did it. I've made a s**t load of wrong decisions in my life. But I know I've made some right ones as well. "They really do rip you apart [in rehab]. You get rid of a bunch of s**t, realise a bunch more s**t, and you make a plan."
Gerard admits he was "p***ed off" that people made assumptions he had sought help for alcoholism as his problem was with pain medication he started taking after suffering injuries in a surfing accident while shooting 'Chasing Mavericks'.
He explained to the November issue of Men's Journal magazine: "I haven't had a drink in 15 years.
"I was actually taking a minimal amount [of pills] when I went in.
"It was more about becoming a mental warrior and not letting pain bother you. The [instructor] would say, 'I don't want to hear about your f***ing MRIs or your f***ing X-rays ... Let's learn how to say to the pain, "F**k you.' "
After the accident - in which the actor was pushed underwater by a wave for almost a minute - Gerard had "visceral flashbacks" which left his mind "in a place where [he] didn't want it to be".