I don't recall ever making a specific, conscious attempt to alter my posture while playing the saxophone. I wasn't really experiencing any physical problems related to the way I was holding the instrument: no aches, pains, not tendinitis, etc. I think it was more of a musical issue. Sometime around my 30th birthday (1999), I "grew up" (or "woke up"!), and finally mustered the discipline and resolve to begin practicing regularly. I think my posture began to change gradually, almost unconsciously, after that. There were many deficiencies in my playing that I realized I needed to address. Just a few of them were poor intonation; a lack of tonal smoothness and consistency; and sloppy, unreliable execution. I found that I could improve in all these areas by holding the saxophone in a way where the mouthpiece naturally reached my mouth (as opposed to bending my head down to meet the mouthpiece). So, little by little, I raised the neckstrap position, bringing the saxophone higher and higher up relative to my head and body. As a result, I think I'm now able to achieve a fuller, rounder, more focused, more consistent tone throughout all the registers; as well as more precise intonation; and more reliability in executing tricky figures (such as fast big-interval jumps etc). Also, around this time I also started exercising more regularly. Now I'm pretty much fanatical about it. Perhaps this has had an effect on my overall posture as well, beyond just playing the saxophone. (My aunt Sharon certainly seems to think so!) I don't know much about coenesthesia. But, sure, the better sense you have of yourself physically, the more relaxed and natural you feel holding the saxophone; the easier it's going to be for you to surmount technical obstacles, to focus on music and to just play. . . .