When people talk about “happiness”, there can be more than a few things we are really talking about. The most common understanding of it is “feeling good”. This relates to hedonistic happiness and the seeking of pleasure while avoiding pain. It is a common approach to happiness, one which has been enshrined in the philosophy of Utilitarianism. It is not, however, the only way to be happy.
http://bigthink.com/scotty-hendricks/three-kinds-of-happiness-and-how-to-achieve-them