Cory Monteith

Cory Monteith says his adolescent years were quite the opposite of the squeaky clean jock he plays on Glee.

"I had a serious [drug] problem," the actor who plays Finn Hudson tells Parade magazine. "I'm lucky on so many counts—I'm lucky to be alive."

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Monteith, who grew up in British Columbia, says he felt like an outsider, and once his parents split up when he was 7, he started to skip school to get drunk and smoke pot. His mother and some friends staged an intervention when he was 19 since they were afraid he "could die."

"That's when I first went to rehab. I did the stint but then went back to doing exactly what I left off doing." Monteith says. The actor eventually cleaned up and began working with an acting coach.

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Now 29, Monteith recently received his high school diploma, and in 2009 he reunited with his father for the first time in 17 years. He says he's opening up about his past so that others know not to give up.

"I don't want kids to think it's OK to drop out of school and get high, and they'll be famous actors, too," he says. "But for those people who might give up: Get real about what you want and go after it. If I can, anyone can."