If you have time to kill but do not feel like going through the motions of unlocking new modes, you can choose the Balance Mode Games -> Marble Drop Game and deliberately fail the first challenge by letting time run out.

Wii Fit rewards you one coin for every one minute of gameplay to unlock new game modes (win or lose). The Marble Drop game takes 30 seconds to fail, but the game rounds up your play time to the closest minute.

This is a reasonably fast way to waste time (and press the A button to continue) if you're looking to unlock modes without earnestly putting effort into it.