I think happiness is a self-feedback system that tells us when we’ve done something right or well. It encourages us to do those things again. Often it stems from other people’s responses to your efforts.
I don’t buy this shit that it is internal, and something you have control over. I don’t think you can just “decide” to be happy. Happy is the joy we feel when we believe we’ve done something well. It can be experienced alone, but even then, it is not purely in relation to you. It is in relation to our ideas about what other people think is good or cool.
I think there are various thresholds for happiness that are determined by brain chemistry. Your feedback system gets out of whack, and presents an extremely high bar in order to feel happy. It’s so high, you can not reach it. Ever. That’s called depression.
Sometimes the bar is so low, people are happy all the time. Then they sit back, relax, and don’t do shit. That’s called foolishness, laziness, or retirment.
The trick is adjusting your threshold for happiness, so it is difficult enough to make you work hard for it, but is not too difficult. You can adjust your notion of “working hard” so that it fits your need for happiness.
Some of us, though, have an extremely difficult time being happy with ourselves. The only way we can be happy is to get our of our heads, and purely enjoy what we’re doing. In a way, we become not ourselves. We sidestep the threshold thingy and go into another set of rules entirely.
Perversely, this usually happens when around other people, but they have all suspended judgment. For the moment, it’s only about fun. The pure joy of doing… whatever. It’s a great relief for people who can never be happy in the judgmental world.