This classic sport is a calorie-torching and body-toning workout but, above all, it's fun and social. Just grab a racket and approach the net.

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Who It's Good For
Anyone who likes social, goal-oriented sports and appreciates a little friendly competition.

Who It's Not Good For
If you've ever had a significant health condition or serious injury, consult your physician before participating in a rigorous activity like tennis, says Nadine Waeghe, a licensed physical therapist and certified athletic trainer for professional tennis players on the Sony Ericsson Women's Tennis Association Tour.

How to Get Started
It's easier than you think: Just enlist a friend and have at it. (If your pals are being lame, find a flat wall or backboard to hit against.) The best way to learn proper form, however, is to take lessons, either privately or in a group (log on to usta.com, the United States Tennis Association's website, to find a local certified instructor). For many, a doubles class is the easiest way to get up and hitting. Usually you can sign up with a friend or be paired with someone at your level.

What to do Before
Warm up with a light aerobic activity, such as jogging around the court for five to 10 minutes. If you're starting to sweat, that's a good sign you're warmed up, says Kerrie Brooks, a licensed physical therapist who works with pro players. Don't bother with any static or held stretches; recent research indicates they do little to prevent injury. Also, drink a glass of water an hour or so before to stay hydrated, and bring a liter to sip between points. If you're playing outside, be sure to apply a water- or sweat-resistant sunscreen, such as Coppertone Sport Continuous Spray SPF 50 ($9, available at drugstores).

What to Keep in Mind
Getting good at tennis is a challenge, but the principles are simple. The most important thing is just to find the ball with your racket, says Bill Mountford, author of "Tennis: How to Master the Game" (Universe, $19). After you've drawn the racket back, focus on pushing the face of it toward the ball, keeping your wrist set at a right angle to the handle. Then start small, playing on only half the court: Hit the ball back and forth at the service line rather than the baseline. You'll learn how to control the ball by hitting in this small space, says Tina Hoskins, a former pro player and author of "The Tennis Drill Book" (Human Kinetics, $20). Later, move to the baseline and, to get into the rhythm of swinging, say to yourself "bounce (when the ball bounces) and then hit" (as you strike).