Celebrities Turning 40 in 2012
Eminem (October 17)
The "Lose Yourself" rapper says he's mellowed as he's gotten older -- and that his art has matured right along with him. "Anything I've ever said, I certainly was feeling at the time," he told the New York Times in 2010, addressing his often controversial past hits. "But I think I've calmed down a bit. My overall look on things is a lot more mature than it used to be."