Walking for Fitness
Walking is a popular aerobic activity. It is easy to do, you don't need special equipment, and it can be done almost anywhere. To get aerobic benefit, you must walk briskly -- fast enough to make your pulse and breathing increase, but not so fast that you can't talk comfortably.
Some people start by walking daily during lunch or after work. Others start more gradually, with a 10- to 30-minute walk every other day. You can add up exercise time over the course of a day or week. Walking 10 minutes, 3 times a day is roughly equivalent to walking 30 minutes, once a day. Build up your walking routine bit by bit, and aim for at least 2½ hours a week of brisk walking.
Getting Started
Start exercising: Many exercise programs say to talk to your doctor before starting. Certain people with specific medical conditions may want to check with their doctor before becoming physically active, however; most people can start a simple walking program without problems. Even those recovering from heart attacks are encouraged to walk treadmills in cardiac rehabilitation programs.
http://www.emedicinehealth.com/walking_for_fitness/article_em.htm
