When you're used to training by yourself, working out with others can be a revelation. Not only can you pick up some pointers from more experienced athletes, but you'll also benefit from having some company. Conversation makes the miles fly by more quickly, of course. But it's the encouragement of people who share your goals and believe in your abilities that can really give you wings. So, too, does the sense that you're doing something meaningful not only for yourself, but for others too.

If you'd like to do good for others as well as yourself, consider the Leukemia & Lymphoma Society's Team in Training. This nonprofit organization provides training for running or walking a whole or half marathon or for participating in a triathlon or century (100-mile) bike ride. You raise funds for leukemia, lymphoma and myeloma and, in return, receive personalized fitness training by certified coaches, lodging and airfare to more than 60 accredited events in the U.S. and abroad. Your personal victory might be cause for celebration for millions worldwide.

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