Obtain a good pair of walking shoes. Mark Fenton, author of "The Complete Guide to Walking: For Health, Weight Loss, and Fitness," recommends a shoe designed specifically for walking or as a second choice, a running shoe. Select a shoe that bends easily through the ball of the shoe but not as easily through the arch. Look for a shoe with a low heel, Fenton suggests. A high heel forces your toes to strike quickly as you walk and can lead to shin discomfort.
Drive around your neighborhood, and map out routes of 1, 1.5 and 2 miles. If you have access to a school's running track, four times around is equivalent to one mile. This will give you a choice of walking distances and an easy way to keep track of your progress.
Train for power walking over a four- to six-week period. At the beginning, walk one mile three or four days per week, and start out at a regular walking pace for 20 minutes -- 90 to 100 steps per minute. Wear a multipurpose pedometer to track your time and steps. Gradually increase your distance, time and steps per minute each week until you're power walking 30 minutes or more at a pace of 135 to 140 steps per minute. Only increase your distance after you're able to walk the set distance while maintaining your target speed.
Prepare your body and muscles with a five-minute, light aerobic warm-up before you start your walking session. Perform a calisthenics exercises such as high-knee marching, skipping rope, jumping jacks or walking lunges. Follow the warm-up with dynamic stretches such as ankle circles, front-to-back leg swings, arm circles and hip circles.
Practice good form. Walk with your head and chest up, shoulders back and your eyes looking straight ahead. Keep your elbows bent 90 degrees and your hands in a relaxed fist. Swing your arms opposite to your legs, forward and backward and not across your body. When your arms move forward, your hands should not go higher than your chin. With each step, land on your heels and push off with your toes. Keep your butt and abs tight, and breathe naturally. Instead of lengthening your strides to walk faster, take smaller, faster steps.
Walk at a slower pace toward the end of your session to cool down, and to allow your heart rate and breathing to return to near normal. Perform a five-minute stretching routine, which helps keep your joints and muscles from becoming stiff or sore. Include stretching exercises for your calves, hamstrings, quads, back and shoulders.