September, 2004 - Jack LaLanne is proof that exercise leads to longevity. This month, the godfather of fitness turns 90, and he still works out every day. Here, the three most important lessons exercise has taught him.

Do something healthy and positive each day. "Whether you take a long walk at lunch or opt for the stairs instead of the elevator, little things do make a difference."

Concentrate on the moment. Don't worry if you missed a day of exercise yesterday. Put all your energy into what your're doing today and what you'll do tomorrow.

Be a role model. "Motivate your friends and loved ones to stick to their routines by being supportive. You can become their workout partner or listen to and be proud of what they've accomplished."