You want to get healthy. you know you need to exercise more. You may have even jump-started your New Year's resolutions by joining a gym. But if you're not ready to squeeze into shorts or a leotard and grunt through an hour of Spinning or Jazzercize or kickboxing, don't despair. There's growing agreement among exercise researchers that the intense physical activities offered by most health clubs is not the only—or even necessarily the best—path to better health. In fact, the best thing most of us can do, say the experts, may be to walk.

Yes, walk. Not run or jog or sprint. Just walk, at a reasonably vigorous clip (3 m.p.h.­4 m.p.h.) for half an hour or so, maybe five or six times a week. You may not feel the benefits all at once, but the evidence suggests that over the long term, a regular walking routine can do a world of preventive good, from lowering your risk of stroke, diabetes and osteoporosis to treating arthritis, high blood pressure and even depression.

Walking, in fact, may be the perfect exercise. For starters, it's one of the safest things you can do with your body. It's much easier on the knees than running and, beyond an occasional stitch in the side, doesn't trigger untoward side effects. If everyone were to walk briskly 30 minutes a day, we could cut the incidence of many chronic diseases 30% to 40%."

Part of the problem is that exercise always sounded so hard. Back in the 1970s and '80s, when scientists conducted a series of studies on the subject, it wasn't clear that exercise could prevent disease at all. In order to prove the point, researchers looked for the greatest effect and found it at the top levels of performance. While the benefits of vigorous exercise are still unassailable, the initial results did not address a more basic question: Is there a lower limit to the amount of physical activity necessary to produce significant health benefits?

The answer, as dozens of studies over the past five years have shown, turns out to be yes. Brisk walking provides many of the same benefits as more intense activities, like jogging or aerobics. The key seems to be in trading off intensity for duration.

Because walking affects you in so many ways at once, it can be difficult to determine precisely why it's good for you. But much of the evidence gathered so far is quite compelling. Some of the areas in which scientists have already identified benefits:

Heart disease
Brisk walking is known to be good for the heart, which makes a lot of sense. The heart is a muscle, after all, and anything that makes the blood flow faster through a muscle helps keep it in shape. But regular walking benefits the heart in other ways as well. It lowers blood pressure, which helps decrease the stress on the arteries. It can boost the amount of HDL cholesterol (the good one) in the blood. It even seems to make the blood less "sticky" and therefore less likely to produce unwanted clots. It all adds up to as much as a 50% reduction in the risk of suffering a heart attack.

Stroke
Until recently, the effect of walking on the risk of stroke was unclear. Some studies showed that folks who are active are less likely to suffer strokes—particularly those strokes that are caused when a clot blocks the flow of blood to the brain. Other studies showed no benefit at all. Then just over a year and a half ago, one of the largest studies to address the issue tipped the balance in walking's favor. In an analysis of the health habits of 70,000 nurses over the past 15 years, researchers from the Harvard School of Public Health found that those who walked the most 20 or more hours per week decreased by 40% their risk of suffering strokes caused by a clot.

Weight Control
The older you get, the harder it is to maintain your weight simply by restricting what you eat. Walking briskly for at least half an hour not only consumes a couple of hundred calories, but it also boosts your metabolic rate for the rest of the day, giving you a better chance of winning the battle of the bulge.

Weight Loss
Walking is a great way to lose body fat, though most people find they have to do it for at least an hour a day in order to lose weight. The body doesn't really start burning its fat stores until after 30 minutes of activity. Exercising too intensely can actually work against you by interfering with the body's ability to pull energy from fat cells. You are more likely to maintain any weight loss you achieve if you incorporate walking into your daily routine.

Diabetes
Two studies last year provided strong evidence that brisk walking 30 minutes a day can postpone and possibly even prevent the development of Type 2 diabetes in people who are overweight and whose bodies have already started having trouble metabolizing glucose.

Osteoporosis
Walking not only strengthens the muscles but builds up the bones to which they are attached. Studies show that women who exercised regularly in their 20s and had a healthy intake of calcium decreased their risk of developing osteoporosis in their 70s more than 30%.

Arthritis
More than 3 million Americans suffer osteoarthritis the wear-and-tear kind of arthritis—of the knees. Walking reduces the pain by strengthening the muscles around the joint. Walking in a pool or gently lifting weights can also help. You may need to exercise every other day to give joints time to recover.

Depression
A quick walk around the block is one way to get a fresh attitude, but can a program of regular walking do anything for clinical depression? New evidence suggests that it can. Antidepressants work more quickly to dispel serious depression, but at least one study found that, after 10 months, depressed patients who were not medicated and started exercising were less likely to relapse than those who took antidepressant drugs alone.

Cancer
Tantalizing clues emerged last year that walking may help lower the risk of colorectal cancer, possibly because walking helps wastes move more quickly through the intestines. Further research is needed, however, to confirm the finding.

Walking won't cure everything that ails you, of course, and nothing happens overnight. "People who have never exercised regularly should not think that in a week they'll solve their problems by walking,"  But they can expect a regular walking program to serve them well into old age.

When you are ready to begin, a few pointers can help you get the most out of your walking routine. First, pay attention to your shoes. If you were a runner, you may need a new pair; runners land on their heels, which is why running shoes have more cushioning at the back. Walkers spend more time with the entire foot on the ground, so shoes for walking need to have more room at the front for the feet to spread.

Second, keep a record of your efforts, including how long you walked and how far you went. There's nothing like toting up the improvements to keep you motivated and challenge you to do better.

Third, prepare yourself properly. The best way to avoid muscle aches is to start slowly and incorporate gentle stretches into your pre-exercise warm-up and post-exercise cooldown.

Finally, set realistic goals. Some people find that walking at a specific time each day works best for them. Others shoehorn walking into their day by making minor adjustments in their daily routines, such as parking the car a few blocks away from the grocery store, taking the stairs instead of the escalator or prodding officemates to break for a walk rather than for a cup of coffee.

Remember: you don't need to win any races to get healthy. The secret to success is to keep a steady course.