As long as you are flailing away at whatever Wii title you're torturing yourself with, you might as well add some resistance.
A patent-pending peripheral called "riiflex" plans to turn your Wiimotes into dumbells through the magic of 2lb and 5lb cases. I have to admit, the design is clever enough, including even a trigger port to allow unfettered access to all the Wiimote's buttons.
Available for preorder deposit (the real price is still undecided, though estimated around $30 per unit), the main nitpick we have so far is that there's no nunchuk version planned...(yet). [riiflex]