My particular bugbear of my job is that every morning, I am supposed to put on the board what sales I will get today. Yes, apparently I'm psychic and know what customers will come in. So, to avoid this, I always put a very low expectation on the board, just above my required minimum (maybe 2 savings accounts for example). That way, I can always beat it. After all, you can never be disappointed if you don't expect much in the first place!
Hey, sometimes it's the only way to recover a day. Look at it like this: I made it through the day still alive, still in good health, still with all my family and friends, still with all the things that matter to me - I'm a very lucky person indeed. Disappointment is just a state of mind. Remember the things you're well off with and also remember my motto: "Change what you can, and don't worry about the things you can't."
Worrying about something you can't do anything about doesn't do you any good!
(Thanks to Comick at NewGrounds for his cute video.)