Cory Monteith's real life teen years were far from the cheery, song-filled existence of his "Glee" alter-ego Finn Hudson.
"I was out of control," Monteith tells this week's Parade, where he admits to skipping school, drinking and smoking marijuana by the time he was 13 -- before eventually quitting school altogether when he was 16.
Of his drug use, the now 29-year-old says he would do "Anything and everything, as much as possible. I had a serious problem," which led to his mother and friends staging an intervention when he was 19.
“That's when I first went to rehab. I did the stint but then went back to doing exactly what I left off doing,” he says -- adding that he finally got back on track after a family member caught him stealing money and gave him an ultimatum: Get clean or deal with the cops.
Monteith says he's opening up about his past to tell "those people who might give up" to "Get real about what you want and go after it. If I can, anyone can."