As someone with chronic depression, I've never really bothered with the question of whether I'm happy so much as just how to cope, regardless of how I feel. And having been suicidal for 20 years definitely puts an eight ball in front of me that's far more important than worrying about whether I'm happy. The last five years of my life have been the high point of my intellectual life. I'm very happy with my choices, and my thinking is of a caliber unseen prior to that time. And I wouldn't call it wisdom, but with age has come clarity about who I am as a person, and why. The absence of existential confusion is a wonderful gift.
That being said, I'm usually too busy reacting to the road in front of me to worry about whether I'm happy or not. Fulfilled, yes. Happy? Tonight, yes. Ask me another time and you may get a totally different answer.