In book X of the Nicomachean Ethics, Aristotle tackles the concept of happiness. Happiness, he says, is not a state because if it were then everyone would possess it, even someone who is asleep throughout his life (we might say someone who is in a coma). Happiness ought therefore to be referred to an activity, one which is chosen for itself and not for the sake of anything else as it does not require anything else, it is self-sufficient.
According to Aristotle we choose almost everything in our lives for the sake of having something else. This is not the same though with happiness because happiness is the goal. He quotes Anacharsis, a Scythian philosopher who visited Greece in the early 6th c. B.C. "Play to work harder" to emphasize his view that amusement is not happiness but a mere form of relaxation as we nobody can work non-stop and needs to relax. Because relaxation is taken for the sake of continuing with another activity (i.e. work) it is not an end in itself.