You know you should exercise, but some days it's tough to get moving: not enough time, too tired, no energy. Counteract those excuses by discovering what motivates you, and use these strategies to develop and maintain an active lifestyle.

Determine an attainable goal such as exercising twice on weekdays, once on weekends. Creating realistic goals will set you up for success. If your goal becomes too easy, you can always design a new one.

Create rewards for achieving your goal. The reward can be a massage, a new workout outfit, a new CD, a session with a personal trainer, or a new piece of sports equipment - whatever you really want.

Partner with a friend, co-worker or loved one - someone who will support you and your goals without sabotaging them.

Subscribe to a fitness magazine or online fitness newsletter. New tips and exercises can be inspirational and alleviate boredom.

Create a competition with co-workers or friends. For example, the team whose members exercise for 30 minutes, three times each week for three months wins a prize. You decide what the prize is.

Change into your workout clothes. Sometimes, it's just a matter of getting dressed that causes the biggest barrier.

Erase the concept that if you can't do at least 30 minutes you're wasting your time. Exercise burns calories, increases energy, and improves your health - even in small doses.

Try a new sport or class. Adding variety, group support and competition can increase your likelihood of exercising.

Make a commitment to your dog to go for a long walk at least twice each week.

Look for ways to incorporate activity into your day, even if you can't do your normal exercise routine. Take the stairs instead of the elevator, go bowling instead of to the movies, or use a push mower instead of a power mower.

Sign up for a race and send in the entry fee. Whatever your activity - running, biking, walking, swimming - there are hundreds of races offered all over the world. Pick a place you've always wanted to visit.

Join a gym. For some, paying for a membership increases the likelihood of compliance. It also eliminates the bad-weather excuse.