If happiness is what you’re after, then you are going to be let down frequently and be unhappy much of your time. Joy, though, is something else. It’s not a choice, not a response to some result, it is a constant. Joy is “the feeling we have from doing what we are fashioned to do,” no matter the outcome.
I'm not arrogant enough to look back on my career and criticize my choices. It's really not my place.