This program begins with short workouts that gradually get longer. By week 10, you'll be walking, swimming, cycling or doing some other aerobic activity for 45 minutes at a time, four days a week. The schedule also includes an optional fifth day of exercise. If you are over 40 or have any chronic medical problems, check with your doctor's office before starting.
Remember, every session should begin with five minutes of very slow and easy walking (or its equivalent). When the session is over, do another five minutes of slow walking to prevent blood from "pooling" in your legs (it takes a few minutes for the enlarged blood vessels to return to their resting size, after exercising).
A useful guide to determining how hard you should push yourself is the rating of perceived exertion (RPE) method of gauging intensity. This method uses a numerical scale, from 1 to 10, that corresponds to how hard you feel you are working. An activity that is rated 1 would be something that you feel you could do for an extended period of time — such as staying in bed and watching television. A 10 would represent an all-out effort — for example, running up a steep hill. Ideally, your main aerobic session (excluding the warm-up and cool-down) should be in the range of 5 to 8 on the scale. You can rate your own effort by selecting the number on the chart that corresponds most closely to the way you feel — how hard you're breathing, how fast your heart is beating, how much you're sweating and how tired your legs feel. Putting a numerical value on exercise is designed to help you maintain a proper workout intensity. For example, you jog a few miles around your neighborhood park and it feels like an 8. If after a few weeks of continued exercise, running those miles feels like a 4, you know that you have to increase your pace to be at an intensity of 8 on the scale.
Easy = 5 or less on the RPE scale
Steady = 5 to 7 on the RPE scale
Brisk = 7 or more on the RPE scale