For me, happiness is the satisfaction that I feel when I have done something well.
For years, I got feedback from crowds while playing music. There isn't much better feedback than getting cheers and applause from people who are spending their hard-earned money to listen to you play and sing. That was easy, when I was able to be in the presence of people wearing colognes, perfumes, and scented laundry products. Those days are over.
Nowadays, things are a bit more subjective, and I have to measure my performance against my expectations. I look at my home, kitchen, wood-pile, garden, etc, and think of what I have done to get this stuff up to snuff and what I have done to help my neighbors with their projects. I spent the entire weekend helping a neighbor and his son tear down and rebuild an old Ford 250. We did seals, gaskets, water pump, electrical parts, etc, and that old work horse is purring like a kitten. I'll help the old man clean and refurbish the body tomorrow or the next day and we'll mount that this week sometime - his son is back in Mass working on a road-crew. I'm pretty happy, though lots of folks in my position would not feel that way. I have a sister who works in health-care and who performs on weekends in a pretty popular band, and she is constantly miserable (or at least wants me to believe that she is miserable and listen to her problems). The happiest times that I have ever seen her enjoy is when I'd get her to sit in with me in my band and we'd do vocal duets on standards like "Brown Eyed Girl", "Mustang Sally", etc, and fill the dance floor.
To people who give a hoot: we are our own worst critics. It is easy to get the popular acclaim of others if you are good at something. It's a lot harder to get your own self-respect when you know your capabilities and feel that you've fallen short.