For many people, this part is even more unpleasant than setting aside the economy size tubs of ice cream and chewing celery all day. Yes, we really do expect you to get up off your fat ass and shift it around in some kind of aerobic activity. If you want to lose two pounds per week, we recommend that you do exercise that will burn 500 calories every day (in addition to reducing your caloric intake by 500 calories per day; see Eat Less). If you want to lose one pound, you do 250 calories worth of exercise per day (and eat less).

How do you know how much exercise you'll have to do to burn your target number of calories? Well, it depends upon your weight and what kind of exercise you do. Heavier people burn more calories during physical activity than lighter people do. More intense physical exercise, such as running, burns more calories than easier exercise, like walking. Find your target heart rate with a target heart rate calculator. Try to keep your heart rate at that level while you exercise.

There are several ways you can find out the calorie expenditures of various forms of exercise for a person of your weight. First, you can look in a book about exercise that has a robust listing of different exercise forms and their caloric expenditures based on various weights (some do not specify weights). Second, you can use this excellent online activity calorie counter. Third, you can use exercise machines, such as stair climbers, treadmills, or stationary bikes that prompt you to enter your weight ahead of time and tell you how many calories you burn during your workout.

Here are some examples of the energy expended by a 150-pound person in 30 minutes of continuous exercise:

Aerobics 200-250 calories Bicycling, Stationary 250-300 calories Bicycling, Actual 300-400 calories Running, 5-6 mph 300-350 calories Stair climber 200-250 calories Swimming laps 350 calories Walking briskly 150-180 calories

As you can see, none of these activities is going to burn up 500 calories in 30 minutes, unless you're much heavier than 150 pounds. We told you it wasn't going to be easy. There are three ways to deal with this: 1) pick a strenuous exercise and do it for 45 minutes to an hour in one session; 2) do a half hour of strenuous exercise and burn the rest of the calories in a second session later (e.g., go for a run in the morning and take a walk at night); or 3) abandon your earlier ambition and just lose one pound a week, which only requires you to burn 250 calories in a day.

Figure out what sort of exercise you're going to do, where you're going to do it, and when you're going to do it, and create a schedule you can follow. It's important to do this before you start, so that you don't become frustrated and quit when you can't figure out what to do. If you like to use exercise equipment and you don't want to buy any, you're going to need access to a gym. If you want to run or bicycle, you need to figure out how to do that without hurting yourself. Sort it all out ahead of time and it'll be a lot easier when you're actually working out.