Bill,
You have touched on a subject that has many different emotions.

Performing --- Love of the music you understand.

Normally people do not stop performing until they are no longer effective. Even then they may keep trying.
Loving the music you understand is different. The joy of creating the music you understand stirs your emotions – there are times when you hate to stop playing. Many years ago when I was playing bars and lounges we played a job that started at 9PM and ended at 2AM. By 2:30AM we had the piano rolled out and played until 5AM.

The sax player in my band was one of the best. He is now 81 and still has a strong desire to perform. Not having the opportunity to perform any longer his sax and flute never leave their cases. His love lies only in performance.

IMHO, John C.

PS, Most musicians have some degree of both. I will play the music I understand until I no longer exist. It still stirs my emotions. I do not get tired of playing the same songs; I can play Misty with 400 variations and different harmonies depending on my mood.