Looking after yourself
Stay out of the downward spiral
Be honest about your feelings, but don't go on and on about feeling bad all the time to anyone who'll listen, it will make you feel worse.
Keep your brain active
Take an interest in what's going on in the world, or at least one area of it. Be enthusiastic about life and never stop learning.
Don't worry, be silly
Learn how to ignore the unimportant things that may niggle you, and break large unpleasant tasks down into smaller, manageable chunks. Keep a sense of humour at all times.