This gleaned straight from a conversation with a friend. One that was on differences in a society and generally turned into one on life and good and bad and corny stuff like that. The key to being happy, we concluded, is focussing on the right things.
When having fun, refrain from saying 'This is the best I've ever had!' Also, never say, 'I've never been in a worse situation.'
It is those who see everything as just 'good' who are happy. That way all your life with all the ups and downs are just 'good'. Things have never actually gone bad. Nor have you a set of memories that you really 'cherish'.
It also helps if you can get yourself to ignore things that should be and are not. The attitude of the set-things-right person causes much anguish to everyone including the person him/herself. I have noticed people who focus on what is, are the happiest. No escapes needed for them. Its a constant breeze.