I'm not sure I've ever known and am not certain I will. I can be happy in a moment, but that goes away. Meds help me shrug it off, and I don't tend to dwell on existential shit like this for long, but like...I dunno that I was cut out for this world, yo.
Also this isn't a cry for help and im not particularly sad or upset right now, I was just walking one of the pups and thought to myself "if I can't be happy I'm gonna make sure these fuckers are."
Happiness as an emotion is a transitory state. Even the periods in my life I look back on as happy times I wasn't happy all or even most of the time. I was dealing with all usual day to day cares and worries of everyday life.
Minimizing suffering, and thus maximizing the ability to experience happiness is a more achievable goal than being happy all the time imo