It's not a question of happiness, it's a requirement. Consider the alternative.
We are all serving a life sentence, and good behavior is our only hope for a pardon.
We may not always get what we want, but surely we will get what we deserve.
Man worships because God lays His hand to the dust of our experience, and man miraculously becomes a living soul - and knows it and wants to worship.
Love is seeing without eyes, hearing without ears; hatred is nothing.
If the destination is heaven, why do we scramble to be first in line for hell?