It is very important to generate a good attitude, a good heart, as much as possible. From this, happiness in both the short term and the long term for both yourself and others will come.
The secret to happiness is short-term, stupid self-interest!
If you want to live a happy life, tie it to a goal, not to people or things.
Short boughs, long vintage.
I have called this principle, by which each slight variation, if useful, is preserved, by the term of Natural Selection.