Don't take any notice of the adverts you see with people jumping around like 3 year olds who have consumed too many E numbers.
Like videogamefreak43 said you CAN sit down and play it infact you should sit down, you don't achieve anything by standing in this game.
You don't have to make massive arm movements to swing Link's sword - flicking your wrist does fine - it doesn't tire you out because you're not supposed to exaggerate, in fact you do the opposite.
Aiming with weapons like the bow & clawshots is ALOT easier than in previous games (you don't have to be precise & the wiimote doesn't pick up the shakey hand effect).
If you didn't have this on the GC then i would advise buying it, however since you do, just spend your money on another game.