Best Answer - Chosen by Voting
Hehehe, I liked Harre's one (thumb up dude)
Well, mine is this: «اعمل لدنياك كأنك لن تموت أبدا, و اعمل لآخرتك كأنك تموت غدا"
It means in English
“Work for your life as you won't ever die, and work for your hereafter as you'll die tomorrow”.
In french :
" Travaillez pour votre vie comme si vous ne mourrez jamais, et travaillez pour l'autre vie comme si vous allez mourir demain "
It’s a Call to be neither extremely positive (materialist) nor extremely negative (too spiritualist), that's how an equilibrated human being can fly with his two wings. (Hahaha, that reminds me of: One hand doesn’t applaud)