The great Robert Louis Stevenson compiled this list of things that were (to him) the key to happiness. It's ironic to me that RLS, ill for much of his life and often suffering, wrote so many things that were positive, including one of my favorites, A Child's Garden of Verses.
How To Be Happy
By Robert Louis Stevenson
1. Make up your mind to be happy. Learn to find pleasure in simple things.
2. Make the best of your circumstances. No one has everything, and everyone has something of sorrow intermingled with gladness of life. The trick is to make the laughter outweigh the tears.
3. Don't take yourself too seriously. Don't think that somehow you should be protected from misfortune that befalls other people.
4. You can't please everybody. Don't let criticism worry you.
5. Don't let your neighbor set your standards. Be yourself.
6. Do the things you enjoy doing, but stay out of debt.
7. Never borrow trouble. Imaginary things are harder to bear than real ones.
8. Since hate poisons the soul, do not cherish jealousy, enmity, grudges. Avoid people who make you unhappy.
9. Have many interests. If you can't travel, read about new places.
10. Don't hold postmortems. Don't spend your time brooding over sorrow or mistakes. Don't be one who never gets over things.
11. Do what you can for those less fortunate than yourself.
12. Keep busy at something. A busy person never has time to be unhappy.
(cited from True Wealth, ed. Gary Morris).