Hartnett was on track to become one of Hollywood's biggest stars a few years ago, but he left "the race" in favor of more satisfying work, World Entertainment News Network reported Tuesday.
"I'm not in that race to be the hottest actor. I was for a couple of years, and it was really uncomfortable. I didn't like that whole world. I think trying to stay on top that way is a shortcut to unhappiness," Hartnett said.
"I'd go crazy doing something I can't believe in. I have to do with what I can do, which is make interesting films we don't see very often, with people who are talented.
"That hottest, newest, greatest thing -- that never really pans out anyway. ... I'm a fan of real storytelling."