This guy did 6-weeks of changing nothing in his life except adding 30 minutes of Wii Sports into his routine and seeing how it'd affect his overall fitness. Surprising (or not depending on how you feel about video games) he actually lost weight, and his overall fitness increased. Take a look at all his results here. I tried a similar experiment, except instead of playing Wii Sports I hate a 30lb steak dinner every night. My results weren't as impressive, although I can no longer see my feet. So that's pretty neat.