Switch Sweat off Something

How about some comments on Switch Sweat off Something?

This is on the lines of harnessing some of the energy spent at the gym in the perennial quest to lose weight and shape up.

I understand making changes to a gym to use the energy from the machines to heat up the pool or showers or laundry are lofty ideas, requiring non trivial investments.

How about smaller targets? Like a small stepper or elliptical machine for use at home, that can charge up an iPod or a cell phone?

This has the obvious advantage of giving a sense of tangible benefits - while losing weight takes ages, I can clearly see my gadgets getting charged and ready for use. This also has the added benefit of reducing ghost power consumption - plugging my iPod into a home exercise equipment means the wall charger is off the plug.

Is this a reasonable target? Can a small generator be incorporated into a basic home exercise equipment and the costs kept low? As of now, basic steppers and such cost less than $50 on Amazon and elsewhere - if it goes to hundreds of dollars, this defeats the purpose.