Courtesy The Hollywood Reporter
09/05/2012 at 04:00 PM EDT
lives a relatively tame life these days, but that wasn't always the case.
The actor, 37, who stars alongside Zoë Saldana
in The Words
, has calmed down a lot since his 20s.
On one occasion, "I was at a party, and deliberately bashed my head on the concrete floor," Cooper recalls for the Hollywood Reporter
in its Sept. 14 cover story. "Like, 'Hey, look how tough I am!' "
The incident, which occurred while he was under the influence, left Cooper with blood dripping from his body, but still wanting more.
"I did it again," he says. "[And] I spent the night at St. Vincent's Hospital with a sock of ice, waiting for them to stitch me up."
This was just one of many moments that led Cooper to much healthier decision-making.
"I don't drink or do drugs anymore," he says, adding that he gave them up at age 29. "Being sober helps a great deal … I remember looking at my life, my apartment, my dogs [when I was still using], and I thought, 'What's happening?' "
Before becoming an actor – and PEOPLE's 2011 Sexiest Man Alive
– Cooper wasn't comfortable in his own skin.
"I was so concerned what you thought of me, how I was coming across, how I would survive the day," he says. "I always felt like an outsider. I just lived in my head. I realized I wasn't going to live up to my potential, and that scared the hell out of me. I thought, 'Wow, I'm actually gonna ruin my life. I'm really gonna ruin it."