If you're a fatty-boom-boom like me, you'll always be looking for things that are almost exercise, but aren't really, so you can pretend you're doing something about your problem while eating another wedding cake garnished with a chop. Nintendo is great at that kind of stuff, and the 3DS will be no different.
The 3DS has a built-in pedometer that measures your steps and encourages walking, keeping the details of your exercise in a backend Activity Log. More than that, however, owners will be rewarded with "Game Coins" which can be used to unlock extra content in 3DS games.
It sounds like a great idea, but it all comes down to support. Will Nintendo get bored with this idea and abandon it as it does so many interesting gimmicks? We'll have to wait and see. Until then, I'm going to have to keep getting fit with Mel B.