What is the minimum amount of time I can spend working out and still see results? I don't have time to spend five hours a week in the gym, and while I know there's no such thing as a quick fix, I'm hoping that a few hours a week will suffice. Thanks.

That's a good question. One of the most common gripes about exercise is that it takes too much time from our already busy lives. The American College of Sports Medicine recommends at least 20 minutes of cardiovascular (aerobic) exercise three times per week and resistance exercise a minimum of twice a week.

Start with 20-minute sessions of aerobic exercise. If you're already active (doing some exercise or participating in a sport more than twice a week), you'll need longer workouts (30 minutes) to make a difference in your fitness level. The same holds true if you mean weight loss when you refer to results: The more time spent exercising, the more calories you'll burn.

Walking is the easiest way to get cardiovascular exercise. If you can cycle or in-line skate a couple of times a week, that would be great to get in aerobic exercise and have fun at the same time.

You can do resistance training in 30 to 40 minutes if you stick to basic movements: Lunges and squats will recruit most of the major muscle groups of your lower body. Bench presses for your chest, lat pull-downs or one-arm dumbbell rows for your back, and overhead presses for your shoulders will take care of your upper-torso muscles. Curls and tricep extensions work for arms. If you perform eight to 12 repetitions of each exercise and do one or two sets of each, you'll get a full-body workout relatively quickly. Use proper form, and don't throw the weights around. Make sure you get proper instruction if you are a novice so you don't waste time doing the exercises improperly.

So if you did 30 minutes of aerobic exercise three times a week and two 45- minute weight-training sessions, you would satisfy the basic parameters for frequency and duration of an exercise program. That's only three hours per week? Not too much to ask, I hope. Of course, make time for stretching.

In six to eight weeks you should notice an improvement in overall fitness and maybe shed a few pounds. To move on to the next fitness level, or to lose more weight, you'll have to increase the intensity of your strength workouts, which will require more rest between sets, and increase the duration of your cardiovascular sessions to increase aerobic capacity and burn more calories.

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