I notice that a debate on happiness is starting up.
As a quality it is not easy to give a precise definitions, but it is a state of mind associated with a sense of completeness - a lack of desire, all needs met. No hunger, no fear, no frustration, no wants. There is a sense of contentment and completeness.
It has two aspects - the environmental and the psycho-spiritual. If the environment cannot supply enough food, water, shelter, warmth and there is waste material in the drinking water, happiness is difficult or impossible.
If the psychological settings or expectations of the individual (or society) are out of kilter, happiness is also difficult or impossible. Perfectionism is the commonest source of this unhappiness, since it leads to a constant gap between reality and expectations. The essence of philosophy should be to produce a state of mind where there is balance betwen tolerance of tolerable imperfections in the environment and intolerance of unnecessary imperfections which are a source of unhappiness to self or others. The spiritual part of psycho-spiritual comes in since the philosopher has to account for and relate to, the inescapable fact of death. Much unhappiness and waste of life arises from fear of death.
So the purpose of life is to learn how to live happily in such a way that everyone else can (at least in theory) live happily - including future generations. We are social beings, and cannot live happily in isolation. The euphoria of a heroin or crack addict is not happiness, since it entails, after the period of contentment, a period of equally acute desire for more.
Of interest to us is the fact that consumerism depends on creating unfulfilled desire by advertising, which says "Buy this, have that , desire the other, and you will be happy."