Don't Fall Off, Dummy
Like with any moving game, it's possible to hurt yourself while playing this, primarily if you fall off. So don't fall off, dummy.
You shouldn't play this game while you're drunk, since you're not likely to have a good sense of balance while you're drunk. Of course, that does give this pretty excellent drinking game potential, but you really shouldn't try. Seriously. Forget I said anything.
Mono Pro: Nintendo explicitly says you shouldn't jump on the balance board. They say this repeatedly in the Balance Board manual and about a dozen times in the Wii Fit game itself. I don't know if they're worried that you'll hurt yourself or if it's really actually bad for the balance board. Either way I'm keeping the jumping ability in the script because it's really intensely fun. But you might be voiding your warranty or putting yourself at risk. Just be aware that Nintendo doesn't like the idea.
Everything else is just common sense. By playing this script you agree that its author is not responsible for any negative consequences that may come from it, including damage to yourself or your equipment.