"Every twenty minutes on the Appalachian Trail, Katz and I walked farther than the average American walks in a week. For 93 percent of all trips outside the home, for whatever distance or whatever purpose, Americans now get in a car. On average the total walking of an American these days - that's walking of all types: from car to office, from office to car, around the supermarket and shopping malls - adds up to 1.4 miles a week, barely 350 yards a day."