Most effective Workout Routines

That said, experts agree that not all exercises are created equal. Some are simply more efficient than others, whether they target multiple muscle groups, are suitable for a wide variety of fitness levels, or help you burn calories more effectively.

1. Walking

Any exercise program should include cardiovascular exercise, which strengthens the heart and burns calories. And walking is something you can do anywhere, anytime, with no equipment other than a good pair of shoes.

It's not just for beginners, either: Even the very fit can get a good workout from walking.

"Doing a brisk walk can burn up to 500 calories per hour, " says Robert Gotlin, DO, director of orthopaedic and sports rehabilitation at Beth Israel Medical Center in New York. Since it takes 3, 500 calories to lose a pound, you could expect to lose a pound for every seven hours you walk, if you did nothing else.

Don't go from the sofa to walking an hour day, though. Richard Cotton, a spokesman for the American Council on Exercise, says beginners should start by walking five to -10 minutes at a time, gradually moving up to at least 30 minutes per session.

"Don't add more than five minutes at a time, " he says. Another tip: It's better to lengthen your walks before boosting your speed or incline.

2. Interval training

Whether you're a beginner or an exercise veteran, a walker or an aerobic dancer, adding interval training to your cardiovascular workout will boost your fitness level and help you lose weight.

"Varying your pace throughout the exercise session stimulates the aerobic system to adapt, " says Cotton. "The more power the aerobic system has, the more capacity you have to burn calories."

The way to do it is to push the intensity or pace for a minute or two, then back off for anywhere from two to -10 minutes (depending on how long your total workout will be, and how much time you need to recover). Continue doing this throughout the workout.