If you're already walking most days of the week for at least 30 minutes, you may be ready to make your routine less routine. Concentrate on increasing distance and speed, gradually working up to 45 minutes.

Speed: Pick up the pace until you're walking a mile in 15 to 18 minutes. (Wear a pedometer, or use your car to measure your route.) To speed up, take faster steps, not longer strides. "There's a physical limit to stride length, but as your fitness improves you can always take quicker steps," says PBS host Mark Fenton, who is also the author of The Complete Guide to Walking for Health, Weight Loss, and Fitness (Lyons Press, $25, www.amazon.com).

Goal: Set your sights on taking 10,000 steps every day, which adds up to about five miles. You'll take half of those steps just by going about your daily life — grocery shopping, climbing stairs, chasing the kids. The rest, about 2 1/2 miles, you'll need to add by fitness walking.

Posture Perfect: Bend your arms to about 90 degrees. That turns them into shorter, more compact pendulums. You'll be able to swing them faster and thus help your legs and feet move faster. (Just try running with straight arms.)