Nick Carter Nick Carter

A sober, healthy and fit Nick Carter says his drug and alcohol addictions were once so severe that he almost died from heart disease. The Backstreet Boy was diagnosed last year with cardiomyopathy, a potentially fatal heart condition that killed Andy Gibb at age 30 and actor Chris Penn at 40.

"[I realized] I don't want to die," he tells People. "I don't want to be that person people read about and think, 'That's sad that he couldn't stop it and killed himself.'"

Carter, 29, had been battling his demons for 10 years. He says not even a DUI, a bar fight and extreme weight gain — he weighed 224 pounds at one point — were enough to make him sober up. Last spring, he underwent testing after experiencing chest pains, but fell into a cocaine binge before the results were due. "I went out and just went nuts," Carter says. "I drank so much and I did a bunch of blow. I felt like I was trying to kill myself — because I didn't want to get the results."

After learning the results and taking doctors' advice, Carter cleaned up his act — though he relapsed early on. The singer says he's now in the best shape of his life at 167 pounds, adding that life is "awesome."