Brave people feels happy by performing endangered things like climbing up the mountain, involved in punji jumping, diving in to the deep sea. A thief steals other things to enjoy that thrill. He needs quick money to spend. He is deriving happiness by that. In short all the action internally wants to end in happiness. But action does not fetch happiness every time. Moreover, even if you get happiness by above actions, it is not long lasting and we again go on repeating the same or search other things to get happiness.
According to certain spiritual tradition, we are spiritual beings in physical bodies. Spiritual beings are always happy. That is the reason happiness derived by outside is not long lasting. Happiness is always here, but covered by thoughts, desires and fears. It is experienced when these covers disappear for a while. When fear or worry comes to an end or a desire attained, there is a temporary disappearance of these covers. The ego and personality stop moving for a while and a great satisfaction and inner happiness is experienced. In order to experience it on a daily basis, one has to learn to calm the restless mind. One has to dive inside, because happiness is an inner attribute and is not in the objects or circumstances. It is in this world, but out of this world.
By following the above technique one can enjoy constant happiness.