Anna Kournikova tells People magazine that the reason she prematurely retired in 2003 at age 21 was because her back injury was so severe. The former world No. 8 is the new trainer of the TV show The Biggest Loser.
"I never planned or thought that was going to be it," she said. "My back really forced me to stop. It got so bad I couldn't tie my shoes, literally. I would be in excruciating pain. I had been doing six to eight hours [of training] every day since I was five years old. It was very interesting to me to stop playing and to figure out, 'Who am I without tennis?' It was very difficult and scary as hell. I did everything from therapy to 10-hour walks on the beach to discover, and think, and try new things."