Answering readers' questions about stretching, interval training and whether sitting on an exercise ball at work does anything at all…What is a good exercise plan for a person who is out of shape? "It's a movable feast" in terms of workout options, says Dr. Michael Joyner, a physiologist at the Mayo Clinic in Rochester, Minn., and an expert on exercise. Pedal or swim if you have a bike or gym membership. But Joyner says walking is the simplest exercise, physiologically and logistically.
New York Times Magazine by Gretchen Reynolds