Casey Meyers (Aerobic Walking) is a man with a mission. He knows that walking is often viewed as the stepchild of aerobic exercise, suitable only for the out-of-shape. And he wants to correct that misconception: in his latest book, he argues that walkers can achieve the cardiovascular fitness level and caloric expenditure of a runner without the injuries. Simple enough for casual exercisers and yet challenging enough to maintain their interest. His walking program increases aerobic conditioning using intensity (how fast), frequency (how often), and duration (how far).60 In chatty prose, he extols the virtues of gradually increasing one's pace from strolling to brisk walking, with the goal being a 12-minute mile. He also dispenses advice on everything from stretching and diet to road safety and how to choose a shoe . His design for fitness may not be glamorous, but it is inexpensive, easy to follow and practical for people from 8 to 80.