I recall the many concerts I attended when I expected to hear great trumpet playing. I paid for the ticket and was never disappointed. The artists delivered no matter what the program. Great players just do that, it's what they do. They may have had huge distractions, a bad day, or a bunch of good reasons why they could have just gotten by with a cranking out of the notes. If they did, I wasn't usually aware of it. Performers perform, they don't complain or offer excuses. I always came home inspired and determined to try to go and do likewise.
Reality would hit soon however. Being able to consistently turn out top quality playing in less than inspiring rehearsals and with a variety of other obstacles, became a much harder assignment than expected. I was usually my own worst obstacle. Encouraging myself, I would imagine the very best players sounding like themselves on any given day wherever. They wouldn't turn it on, and then allow it to be turned off. Great playing always defined them regardless of their externals.
So the challenge and measure of greatness is the ability to create as many high moments in music as possible. This does not mean being the loudest player on the stage or the most egotistical. It means being able to enjoy playing as much as possible while contributing to the success of the ensemble, and making the listeners feel they got what they paid for. In short, it means producing many more "highs" inspite of the "lows" that accompany daily routine. The audience has their own lows. They come to escape and to hear some musical highs.
I remember a great cellist resolving that his own musical fulfullment was not going to be determined by any conductor. His contribution of musical highs was going to be controlled by himself and not dependant upon favorable circumstances or the lack thereof.
How many highs are you experiencing? Or are the lows keeping you in chains? Easy to talk about, very hard to execute, but a goal worth keeping in focus.