When people start an exercise program, some lose a lot of weight, while others lose nothing. An effective exercise program for weight loss should 1) be continuous, 2) use all of your major muscle groups, 3) include one intense workout a week for each muscle group, and 4) be done on land, rather than in the water.

Stop-and-start exercises, such as lifting weights, do not require that you use your muscles continuously enough to burn a lot of calories. Activities that use just one muscle group, such as doing situps or pushups, won't help you to lose a lot of weight because the stressed muscle groups tire quickly so you can't exercise very long.

Exercising at a leisurely pace won't help you lose a lot of weight either. You burn calories while you exercise and after you finish exercising. Intense exercise raises body temperature which continues to be elevated and burn more calories for several hours after you finish exercising. This also explains why swimming is not the best exercise for weight loss, because water conducts heat away from your body so fast that your temperature does not rise. When you exercise on land, air insulates your body so your temperature rises.

Pick sports in which you can exercise intensely, but don't exercise very hard in one sport more often than once a week. Every time that you exercise, your muscle fibers are torn slightly. You can tell this has happened to you when you muscles feel sore on the day after you have exercised. If you exercise intensely on days when your muscles feel sore, you are at increased risk for injuring them. If you want to exercise vigorously every day, you should choose two sports that use different sets of muscles, such as cycling and rowing.