context: If you don't love working up a sweat but do love the benefits of a cardio workout, swimming may be your ideal match. The water keeps you cool, even as your heart gets a great workout. You'll probably be able to keep yourself going for a longer time than if you were running. That's because it's fun and gentle on your joints and muscles. The water can also feel relaxing. Plan on doing 2 1/2 hours of swimming a week. Or mix in swimming with other cardio workouts. You can set your own pace, going as fast as you like. Most people swim laps in a pool. If you swim in an ocean or lake, make sure you know how to stay safe in open water with currents. If you don't already know how to swim, there are classes at community pools, gyms, and YMCAs or YWCAs. It's good to know how to swim, for safety's sake, even if you aren't planning to make swimming your main workout. You'll use your lower and upper body muscles for a steady workout. You can make your swim harder by going faster or longer. Core: Yes. Swimming gives your entire body a great workout, including your core. Arms: Yes. You'll need your arms for most swim strokes, so expect them to get a workout. Legs: Yes. You'll use your legs to propel yourself through the water. Glutes: Yes. Swimming uses your glutes. Back: Yes. Your back muscles will get a workout, whether you're doing the backstroke or a water-based exercise class. Flexibility: Yes. Swimming will make you more flexible. Aerobic: Yes. Your heart will keep pumping as you use your entire body to move through the water. Strength: Yes. You'll get stronger from the resistance of the water, which is about 12 times the level of air resistance. Try using hand-held paddles, foam noodles, or a kickboard for extra resistance. Sport: Yes. You can compete at any age, and join a team. Low- Impact: Yes. Swimming is an excellent low-impact workout. The water gives you buoyancy, so you'll float through your exercise session without putting pressure on your joints. Cost: You'll need to pay for access to a pool, unless you have one where you live or you're swimming in a lake or the ocean. Good for beginners? Yes. You may not be able to swim for a full workout (30 minutes or longer) right away, but you can work your way toward a longer workout. Start slowly, with 5-10 minutes of laps. Outdoors: Yes. You can swim in indoor pools, too. At home: Yes, if you have a pool. Equipment required? None, except for a swimsuit. Goggles and a swim cap are optional. To mix things up, you can add small accessories to your water workout, like kickboards or swim noodles. If you are looking for a great aerobic and total body-strengthening workout, then look no further. Swimming can provide all that and more. If the water is warm, swimming can even have a soothing effect on achy joints and muscles. If the weather is hot, swimming can keep you cool while you burn calories, shed extra pounds, and get in shape. Of course, you need a safe place to swim. Pools are ideal. If you are going to swim in lakes or oceans, you have to be very careful of currents, water temperature, and other obstacles. And never swim alone -- either inside or out. Swimming can be a solo or a group adventure. You may prefer to swim laps, if you like to work out by yourself. But if you like being in a group, many pools and Y's have aquatic exercise classes for all levels. If you are older, pregnant, or disabled, there is likely a specialized class just for you. Is It Good for Me If I Have a Health Condition? Swimming is just about as good as it gets for a total workout. If you are pregnant, the buoyancy of the water will take stress off your joints. If you swam before you became pregnant, you will likely be able to continue swimming unless you have a problem with your pregnancy. There are just a couple of things to consider. Make sure that the water is not too hot or too cold. And if the breast stroke worsens any existing pelvic discomfort, choose another stroke and talk to your doctor or midwife. Swimming is a great aerobic workout for people with most types of arthritis. It can take the load off your joints and help prevent injuries. It is also a good choice if you have low back pain. Warm water can be very soothing. Check with your doctor first if you are having joint pain, have had a recent injury, joint replacement, or are having an arthritis flare. If you have diabetes, an aerobic activity like swimming can be a very important part of your diabetes treatment plan. It will help you burn calories, lose weight, and keep your blood sugars under control. If you have high cholesterol, you will also benefit from swimming. It will help you lower your ''bad'' LDL cholesterol and raise your ''good'' HDL cholesterol. If you have been a couch potato, or you have heart disease or other medical problems, check with your doctor first to see what kind of swimming program is right for you.