Fitness is a step by step progression, Dr. Nelson says. If you're already fairly active or you've recently succeeded in adding more phys ical activity to your lifestyle the next step to getting fit is simple: Whatever you're doing now, do more.

This is where aerobic exercise comes in. But don't worry. You still don't have to join a health club or take an aerobics class (unless you want to). The great thing about aerobic exercise is that there are so many different activities to choose from dancing, biking, swimming, playing tennis. The Est goes on and on.

No matter which activities you choose, you'll get the most out of your workout if you follow these practical pointers.

Put on your dancing shoes. If you're dancing, that is. And running shoes if you're running. Walking shoes if you're walking. You get the idea. "As we get older, our feet, ankles, shins, and knees are more vulnerable," says Joan Price, certified fitness instructor, speaker, and writer from Sebastopol, California, and author of Joan Price Says, Yes, You Can Get in Shape! "Wearing the right shoes for your activity can protect you by cushioning and stabilizing your feet and basically serving as mini shock absorbers."

Seek out support. When you work out, make sure that you wear an appropriate sports bra that holds your breasts close to your body, Dr. Nelson suggests. Otherwise, all the movement that's involved in aerobic exercise can start your breasts sagging southward. "It amazes me that a lot of women don't wear a sports bra when they exercise," she says. "When you don't, the repeated movement will actually stretch the breast tissue and make it less elastic."

Warm up. Your car isn't the only thing that needs to be warmed up before all its parts are lubricated and ready to roll you have your own engine and parts that need to run a few minutes before shifting into high gear. "A warmup provides a gradual transition from rest to the physiologic demands of exercise," Dr. Pate says. Basically, a good warmup gets your blood pumping, limbers up your ligaments and tendons, and loosens your muscles so that you reduce your risk of injury.

Light stretching and a slow version of the activity you're about to do work best, Dr. Pate says. Walk more slowly before you pick up the pace, for example, or swing the racket and hit a few balls before playing a round of tennis. You could even march or jog in place anything that gets your arms and legs moving for 5 minutes.

Cool down and stretch. Your body needs to downshift its gears slowly, rather than going from brisk walking to a sudden halt. The cooldown is similar to the warmup, only instead of gradually picking up the pace, you gradually slow it down. This lowers your heart rate gradually so that you don't feel dizzy or faint, Dr. Nelson explains.

After your workout is also the best time to stretch because your muscles are still warm. A good 20 to 30 second stretch of each of the major muscle groups that's your arms, legs, abdomen, back, and rear end helps to build flexibility and prevent injury.

Beat blisters. Whether you walk, jog, hike, or hit the tennis courts, a bad case of blisters can put the brakes on your physical activity fast. To prevent blisters before they start, cover your clean, dry feet with your regular antiperspirant, suggests lead researcher Joseph Knapick, Sc.D., at the US. Army Center for Health Promotion and Preventative Medicine in Aberdeen Proving Ground, Maryland.

You can use any kind spray, stick, or roll on. Just make sure to hit every nook and cranny of your feet. Try it every day for 5 days before your run or hike, or use it once or twice a week indefinitely. It works by reducing sweat, which creates the friction that causes blisters. And it helped 80 percent of U.S. Army cadets stay blister free after a 13 mile hike.

One note of caution: If you develop a rash or experience any skin irritation, try using the antiperspirant every other day or switch brands. If the irritation continues, stop using it.

Drink up. When you exercise, you sweat out more fluids than you would just sitting on the couch. And since your muscles are about 70 percent water, you need to replenish those fluids so that you don't start to feel weak before your workout's over. A good rule of thumb is to drink an 8 ounce glass of water before and after you exercise and to have half a cup every 15 to 20 minutes during your workout, says Felicia Busch, R.D., a nutritionist in St. Paul, Minnesota, and a spokesperson for the American Dietetic Association.

Leave your worries behind. To get the relaxation benefit of exercise, you have to wind down while you're working out. We already mentioned a study conducted at the University of Georgia in Athens where stressed out college students cut their anxiety in half by riding exercise bikes for 20 minutes. Simply taking time out from daily worries may have been responsible for the drop in anxiety, the study authors say, because another group of women who studied while riding still had high anxiety levels afterward.

Add weights to firm flab. Many experts recommend combining your aerobic exercise with strength training. Why? Because together they give your flab a one two punch. "Aerobic exercise burns fat while strength training tones muscle," Dr. Nelson says. And the result is a firmer, shapelier body.

What's more, strength training gives your metabolism an extra boost by building muscle, which burns more calories.

And the stronger your muscles are, the more you'll get out of your aerobic workout. "You'll be able to exercise longer, and you won't feel as tired afterward," Dr. Nelson says.

Slow down the music. The aim isn't to add romance to your workout, but to keep the music at a comfortable pace, especially if you're participating in an aerobics class that requires fancy footwork or using a step. "The music should be slow enough for you to put your foot all the way down," Price says. "Staying on your toes because the music is too fast puts you at risk to injure your foot or leg." If you feel uncomfortable asking the instructor to use slower music, or if you're using a workout video and can't change the music's speed, then do the move at halfspeed, she suggests.

Make it fun. When we were kids, exercise was a ball. We sprinted up the stairs, we ran home for dinner, we jumped when we heard something exciting, and we looked forward to recess. "Exercise should still be playtime," Dr. Ross says. "Most women have so many responsibilities in addition to their jobs that if exercise becomes just one more thing on our 'must do' list, we won't stick with it. That's why I encourage women to find something that's fun. Put the kids in a stroller and the dog on a leash and go for a walk. Dance with your husband for 15 minutes before you sit down to eat. Take the kids roller skating or ice skating. Or go for a bike ride."

Grab a partner. Even if you're not square dancing, a partner can help you out in several ways. First, she can motivate you when you're feeling tired or discouraged, Dr. Nelson says. Second, exercising with a friend can turn your workout into a social activity so it's more fun. And most important, a friend can help you stay committed. If you don't feel like exercising but your friend is counting on you, you're more likely to put on those sneakers and hit the road.

Stick with it. Cardiovascular fitness requires maintenance. If you work out 5 days a week for several weeks, for example, and then cut back to exercising just 1 day a week, you'll lose 90 percent of your gains in 12 weeks, Dr. Duncan says. So do yourself and your heart a favor and make exercise a permanent part of your routine.