(MONEY Magazine) – Before there were treadmills, elliptical machines, ergometers and Ab Scissors, there was walking. And in the 2 million years since Homo erectus started humankind ambulating without the aid of knuckles, putting one foot in front of the other has established itself as more than just a fitness fad. Some 54 million people walk as exercise today, according to the Sporting Goods Manufacturers Association, and no wonder. It requires merely the oomph to get off the couch and the wherewithal to buy a good pair of sneakers.

You can make your strolling a bit more purposeful, however, by adding a pedometer to your walking gear. In the past several years, health and fitness experts, including the former surgeon general, C. Everett Koop, have made the case that 10,000 steps daily, the equivalent of five miles, is the right goal for achieving lower blood pressure, better glucose control, a healthier heart and a trimmer physique. "We've found that people going about their everyday activities take 6,000 steps, and another 4,000 is the equivalent of adding two miles, or another 35 minutes, consistent with recommendations by the American College of Sports Medicine," says Dixie L. Thompson, a professor of exercise physiology at the University of Tennessee, Knoxville.

A pedometer can spur you to reach that goal. These devices detect body motion and record each step. Some use a spring-levered mechanism that swings like a pendulum and clicks for every step; others, called accelerometers, use sensors that translate movement into electrical charges. For as little as $8, you can get one that measures distance walked and calories burned. More advanced ones—generally those $30 and up—may come with extras like a heart-rate monitor, a radio or a memory that tracks progress over time.

At the minimum you want an easy-to-read display and a clip strong enough to hold on tight (most pedometers attach to the waistband). Careful: There are many inaccurate models on the market, some miscounting steps by as much as 40%. (Those we tested, however, were all within 6% of the correct count.) Thompson advises buying from a store with a generous return policy, taking the unit home and testing it by walking 100 steps. If it's off by more than five, or 5%, try repositioning it, since a pedometer's angle or proximity to your waist sometimes makes a difference. If it still doesn't deliver 95% correct results, try another model.

Whichever kind you choose, your new pedometer can help you step up your workout. "Setting goals and self-monitoring can really help change your behavior," says Thompson. "With a pedometer, you'll know how close you are to your goal, and maybe it'll motivate you to take a walk at lunch."

How we did it Since weight affects performance, we had both a heavyset male and a petite female use five widely available pedometers on different surfaces and at varying speeds. To test accuracy, our subjects walked 100 paces on flat ground three times. To test ease of use, they sauntered, strolled and stepped until they were blistered, achy and ready for a nap.

WHAT TO LOOK FOR

Omron's Pocket Pedometer HJ-720ITC is a great tool for walkers because it's:

› Relatively accurate and performed well without a lot of repositioning

› Easy to attach to clothing but also works carried inside a pocket

› Full of features, like a seven-day progress log and a USB hookup