Actor Dennis Quaid admits his "biggest mistake" was his addiction to cocaine and candidly writes about his struggle in a Newsweek article.

Quaid, who stars in this month's 'Soul Surfer,' reveals he was introduced to the drug when he moved from Houston to LA in 1974. "It was very casual at first," he says of his drug use. "That's what people were doing when they were at parties. Cocaine was even in the budgets of movies, thinly disguised."

"It was supplied, basically, on movie sets because everyone was doing it," he continues. "People would make deals. Instead of having a cocktail, you'd have a line."

Quaid says his drug use contributed to his inability to handle his new fame and he essentially turned into a different person.

"I was doing my best imitation of an asshole there for a little while, trying to pretend everything was OK," he reveals. "Meanwhile my life was falling apart, and I noticed it myself, but I was hoping everyone else didn't."