A Most Unwelcome Set of Facts

http://www.slate.com/id/2275789/

On average, a treadmill uses between 600 and 700 watts of energy. That's the equivalent of watching three or four 46-inch LCD televisions or leaving 50 compact fluorescent light bulbs burning, for the duration of your workout. If you ran for two-and-a-half hours per week—the government's recommendation for ordinary adults—generating electricity for the treadmill would emit about 110 tons of carbon dioxide annually. (That's about 1 percent of the annual CO₂ emissions of the average car.)

As though Laziness, Boredom, and a Silk Duvet were not already Barriers Enough-- Now a Moral Argument.