I don't really have any sayings which I live by but I do often rant at people who exclaim "FML!" and "My life sucks!". My rant usually goes along the lines of "are you blind? Are you deaf? Are you a paraplegic? Are you homeless? Do you have aids? No? Then stop your fucking bitching!" Too many people get depressed for too many reasons. Just be happy!
Compared to so many, your life is the best life in the world, so shut up and enjoy it! ...yeah, I think that's my general outlook, and it's the reason why I'm so happy all the time