Instead of wishing your friend good luck, how about telling them “YOU ROCK”
As I see it, luck has nothing to do with whether you make it or not … it’s all YOU! Do your best at any given point in time, and you have nothing to worry about; simply because, you can’t do more than your best … so, you see, luck has nothing to do with it!
Give it a shot … replace “GOOD LUCK” with “YOU ROCK” .. I even made it rhyme, so you wouldn’t feel completely alienated by the novelty!