I was watching a 60 minute interview with Paul McCartney last night. The interviewer showed Paul a clip of the famous concert on the roof of Apple studios. She asked why they looked so happy if they were breaking up?
In my mind there are very few things in life that are as much fun as performing music with friends. In our case it is 6 of us, in time, on pitch performing a song that in many cases we wrote. The audience is smiling or tapping their feet. That tells us that we sound good. What really feels good is how connected we are on stage. People tell us we look like we are having fun. We are. It does not matter that we are not well known. We could be playing in front of a hundred people or just for ourselves. For me, the reward for working on my musicianship is the connection with my friends making music.
I would guess that is why the Beatles were smiling that day.