This article is from the Aerobics Fitness FAQ, by firstname.lastname@example.org (Robles) with numerous contributions by others.
It is a good idea to start slowly and build up to a full
program. Walking is the easiest way to begin a program.
Start with a stroll for a mile or so and build up to walking
3-4 miles per hour. As you become proficient at walking,
you might want to try another activity such as jogging,
running or even aerobic or step classes. The best aerobic
program is the one you enjoy and will stick to. Remember,
the journey of 1000 miles begins with but a single step.