Fitness Secrets From A Tennis Legend

Martina Navratilova is one of the greatest players ever to step onto a tennis court. Even as she's pushing 50, she's able to compete against women many years younger. She came out of retirement to play doubles in 2000 and was back on the court this past weekend, reaching the doubles finals at the Nasdaq-100 in Miami.

These days, Navratilova is inspiring awe not only for her tennis, but for her amazing physical condition. She shares her diet and fitness secrets in a new book called "Shape Your Self," and joined The Early Show Tuesday to discuss some of her suggestions.

"I was asked so many times by friends and media, how do I do it. And I realized I knew a lot more than I thought I did, and I really wanted to share and help people with that knowledge," she told co-anchor Harry Smith. "I've lived this for close to 30 years."

Navratilova admitted that when she first retired, she let herself slip — but quickly regretted the lapse. "I didn't put on much weight, maybe five to 10 pounds," she said. "But I got really sluggish, and I was too tired to do the sports that I love doing. And I thought, this is really silly. So I started getting back in shape so I could do everything that I wanted to do."

Fatigue is one of the complaints Navratilova says she hears most from other people and it's a condition she says is worth fighting. "It's really about having the energy of doing your everyday things. And most people, you know, don't have enough. They just keep saying, 'I'm tired. I'm tired.' You should be tired of being tired."

The tennis star says the most important thing is to think carefully about the kinds of foods you eat. "You cannot feel energetic when you're eating lousy food. And what I ask people to do is to do it in little baby steps. Make the changes little by little. Everybody can drink just a little more water, and just that will make enough difference to make you feel better and want to get up in the morning," she told Smith. It might take a week or two, but "you will start feeling the difference, and you will start looking different. The skin is going to start looking better, and your friends will say, 'What did you do?'"

Watching what you eat does not mean giving up everything you find delicious. "Food is your friend. I love to eat. I live to eat," said Navratilova. "I know what I'm eating. It's not processed, not chemically altered. It's the real deal."

And while exercise is important for supporting a healthy lifestyle, be realistic about what your body can handle, said Navratilova. "Don't overdo it. You need to take it easy, listen to your body and pay attention. That's why I haven't had the injuries that most people have — because I pay attention. It's not about being a great athlete. It's having the mentality of an athlete."

In "Shape Your Self," Navratilova guides readers toward their fitness goals with simple healthy recipes and exercises. She has more information on her Web site www.martinanavratilova.com.

To read an excerpt from "Shape Your Self," click here.