before you do something that you've been practicing for, people always say "good luck," which struck me a strange, after all, the person practiced for it, doesn't that decide how well they preform?

i guess you could mean good luck as in nothing crazy happens, but it still gives the impression that there is a factor of luck involved, when in reality there is not much.

if we want people to be more motivated to prepare for things, perhaps changing our language slightly would help achieve that goal.