When you work with someone in the voice studio, you see certain things, things which aren't readily explainable. One of them is that the face and body begins to looks sculpted, even beautiful. Most people think this is a result of the emotional affect of the song being sung, but I believe more is involved. Of course, I think it has everything to do with the ear.
Teachers and students often talk about alignment, and this makes a lot of sense, because the spine is observed to be elongated and the ribcage open when everything is going well. That's what students stay if you stop and ask them how they feel, after all. How does this expression of the body arise? The way I see it: it's simple basic stuff, one thing being the acquisition of clear, full and free vowels, the student mining and mixing their essential qualities. But that's not how most of us think. Instead, we think alignment can be, and should be, imposed from without. To me, that's like plastering a smile on your face, which, by the way, messes with the ear's ability to process sound. You see politicians do it all the time, being trained to grin, grin, grin no matter what mess they've gotten themselves in. I, for one, never believe what I hear.
You may be surprised that I don't insist on beautiful sounds. That's not how it works with me. I don't impose tone onto the student. What do I do instead? Teach students to sing /i/, /e/, /a/, /o/ and /u/, the five vowels being nothing less than asana for the ear. Everyone has to do them, be they Broadway babies or budding operatic baritones, the difference being the baritone usually has to go deeper into each pose and hold it longer, classical singing being rather formalistic. This is why the Old School kept the latter practicing vowel sounds on elaborate scales for a long time. They shape the body and result in the singer finding his voice.