From the Smithsonian,
Why does it seem we’re hard-wired to want to feel happy, over all the other emotions?
That’s a $64 million question. But I think the answer is something like: Happiness is the gauge the mind uses to know if it’s doing what’s right. When I say what’s right, I mean in the evolutionary sense, not in the moral sense.
Nature could have wired you up with knowing 10,000 rules about how to mate, when to eat, where to seek shelter and safety. Or it could simply have wired you with one prime directive: Be happy.
You’ve got a needle that can go from happy to unhappy, and your job in life is to get it as close to H as possible. As you’re walking through woods, when that needle starts going towards U, for unhappy, turn around, do something else, see if you can get it to go toward H. As it turns out, all the things that push the needle toward H—salt, fat, sugar, sex, warmth, security—are just the things you need to survive. I think of happiness as a kind of fitness-o-meter.
…when that needle starts going towards U, for unhappy,
turn around, do something else,
see if you can get it to go toward H.