Fitness means being able to perform physical activity. It also means having the energy and strength to feel as good as possible. Getting more fit, even a little bit, can improve your health.

You don't have to be an athlete to be fit. Athletes reach a very high level of fitness. And people who take brisk half-hour walks every day reach a good level of fitness. Even people who can't do that much can work toward some level of fitness that helps them feel better and have more energy.