Happiness is a state of mind, and is a (mental, emotional) place, and that place is easier to occupy if your life is setup to make it easier. A few good friends, a romantic partner, meaningful work, kids is sort of the usual and probably pretty safe recipe. It's possible to have these things and be miserable, and it's possible to have none of them and be blissfully happy.

Aristotle wrote a pretty solid book on the topic.