Walking can be a lifesaver

Almost every day during her lunch hour, JoAnn Manson goes outside for a brisk 20-minute walk. And on weekends, she takes an hour-long hike with her family on both days.

At times, the doctor has so much to do that she is tempted to skip it, but she doesn't. She knows better than almost anyone else that a simple daily walk is a prescription for better health.

Research by JoAnn Manson, a professor of medicine at Harvard Medical School, shows that regular physical activity can reduce the risk of many diseases, lead to a longer life and help control weight.

"If someone said there was an elixir that reduces your risk of almost every major disease, wouldn't everyone be clamoring to get ahold of it?" asks Manson , a professor of medicine at Harvard Medical School and chief of preventive medicine at Brigham and Women's Hospital in Boston.

"I'm convinced from the research that a sedentary lifestyle kills you, and moderate activity like walking can be a lifesaver."

But this elixir obviously isn't as easy to take as a teaspoon of medicine. Despite the evidence of benefits, 75 percent of Americans do not meet the government's recommendation of getting at least 30 minutes of physical activity on most days of the week. Experts say this lack of exercise is taking a toll on Americans' health and their waistlines. Almost 65 percent of adults in the United States are either overweight or obese.

Walk briskly, or climb a mountain

Moderate activity could be a brisk walk (a mile in 15 to 20 minutes or less). It means walking as if you have some place to go, at a rate where you can feel your heart rate go up. Vigorous activity could be jogging, hiking up a mountain, biking over hills or playing racquet sports.

Manson, co-author of "The 30-Minute Fitness Solution" with Patricia Amend (Harvard University Press), believes many people don't exercise because they think they have "to do a high-intensity sweating activity or they are not going to get any benefits, so they decide they might as well be a couch potato."

Your heart will thank you

But sedentary people who start doing moderate amounts of activity get a big jump in health benefits, she says. There is additional gain from going from moderate to larger amounts. For example, women who walk 30 minutes a day reduce their risk of heart disease by 35 percent; those who walk an hour a day reduce their risk by half.

One simple way people can make sure they're doing enough activity to reap the health benefits is to work up to walking at least 10,000 steps a day, Manson says. To keep track of that, they can wear a pedometer, or step counter, on their waistbands.

Walking a mile is roughly 2,000 steps. Some office workers who sit most of the day take less than 4,000 steps.

So to reach 10,000 steps, that person would need to take a brisk walk or two every day in addition to pacing while talking on the phone, taking the stairs whenever possible or walking around the office or house, she says.

Manson says that before she started wearing a pedometer, she was walking about 7,500 to 8,000 steps a day; now she does between 9,000 and 12,000. She also weight-trains twice a week for 20 minutes.

People who are trying to lose weight should cut calories and may need to do an hour of activity a day, she says.

Manson knows that people are busy, and that many don't make exercise a priority. But she says action breeds motivation. If people would set a simple goal for themselves, such as walking 15 minutes in the morning and 15 minutes in the afternoon, then it should become a habit after a few weeks.

"Walking doesn't take a tremendous amount of time," she says. "All it takes is a good pair of walking shoes — and commitment."