WRIGHTSVILLE, Georgia -- Many people think they know the legendary Herschel Walker: 1980 Heisman Trophy winner, pro football star, Olympian and last week in San Francisco, an Olympic torchbearer.But not only did the public not know the real Herschel Walker, the athlete himself said he didn't either. In his just-released book "Breaking Free," Walker reveals he has a form of mental illness called dissociative identity disorder, or DID, formerly known as multiple personality disorder. "I didn't really learn about this until about 10 years ago," Walker tells CNN. "My life was out of control. I was not happy, I was very sad, I was angry and I didn't understand why." Walker said his life went off the tracks shortly after his football career ended and when his now ex-wife was expecting their son, Christian. The book, he said, is about coming to terms with his diagnosis. He hopes to educate the public and break down stereotypes about this disorder. Whe...