ATLANTA, Georgia (CNN) -- Lois Fletcher started taking the subway to work nine months ago to save money. It turned out to be an excellent way for her to lose weight -- more than 30 pounds to be exact.
By walking the mile from the train station to her job, Lois Fletcher has built exercise into her daily routine.
Five mornings a week, the 53-year-old mother of three boards a commuter train in suburban Atlanta, Georgia, and heads downtown. She then walks about a mile to her office at the American Cancer Society, where she works as a computer specialist.
"My doctor has been encouraging me to exercise for quite some time," Fletcher said. "I've never been able to fit it into my schedule. Now it is part of my daily commute."
Like millions of mass transit riders around the United States, Fletcher realizes that leaving her car behind and getting on a train is good for her physical and mental health. 
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Fletcher acknowledges she's overweight. When she started walking to and from the train station, she weighed close to 300 pounds. She suffers from diabetes and was taking medication for hypertension.
She was surprised to see all that walking was paying off: "At first I started to see changes in the way my clothes fit, and then when I got on the scale I found I had indeed lost weight."
"Here's somebody in her work clothes, granted with tennis shoes on, getting good exercise," observed Fletcher's colleague, Colleen Doyle, director of nutrition and physical activity for the American Cancer Society. Doyle herself makes the same trek from the subway station to the office. Going to a gym isn't the only way to get regular exercise, she said.
Doyle said she sees more and more people who are killing two birds with one stone and meeting daily physical activity recommendations by walking or biking to work.
Doyle said 30 minutes of moderate exercise at least five days a week will not only help people manage their weight and blood sugar levels, but may also help prevent some cancers by controlling hormone levels.
The Cancer Society isn't the only organization encouraging the mass transit exercise trend. The Atlanta Clear Air Campaign is helping commuters such as Fletcher log their progress using an online calculator. The program offered Fletcher added incentive to take mass transit by paying her $3 a day so long as she recorded her daily mileage on the train.
Subway riders from Los Angeles, California, to suburban Washington are getting information on the benefits of taking mass transit and walking to their destinations.
Doyle encourages Fletcher and others to walk faster. Doyle also suggests incorporating strength-training exercises into a workout routine to build strong muscles and bones. She adds eating a healthy diet that includes fruits and vegetables and whole grains goes a long way toward improving overall health.
Now that she's found a way to exercise, Fletcher plans to focus on her diet in order to achieve her goal of dropping 90 more pounds.
She credits her daily walks with changing her life. "It's amazing how a small change in your lifestyle can have huge benefits in my quality of life," she said. "I feel better and now I can see how I can drop the rest of the weight." E-mail to a friend 
Judy Fortin is a correspondent with CNN Medical News.
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