The very simple equation to feeling good.
Have you ever noticed that when you are doing things you love, working towards a goal that is meaningful, or contributing to the greater good it just FEELS AMAZING? And when you are neglecting yourself, your dreams, or working towards something that is not meaningful to you, you feel bad? You may even get depressed, angry, or blame yourself.
Our biology has evolved to SHOW US HOW TO FEEL GOOD.
The FLOW research also backs this up.