When I practice the clarinet, I try to start from a blank page, blowing warm air from my heart, not judging what comes out of my instrument. That's me flowing out the other end (among other ends) and I best not trash it. At first it's huffy and airy and fuzzy. But eventually it starts to refine itself, flowing into a satisfying resonance, with the depth of character I seek. And if not, I try to stay emotionally open to let it happen when it will.
I always keep the ideal of the perfect sound in my ear, to guide me and my instrument toward it. I never reach it. That's the curse of the performer, to struggle toward an unreachable goal. But to shimmy close to that pure ideal even a few times in a career is the musicians blessing. For me to be able to express and make real the elusive perfection of music is my greatest challenge and my greatest gift.