There is no way around it; you must get to know your body well in order to sing well. You need to find out how to treat it as best you can and how to listen to it – how to be with it, cooperate with it, and use it to the fullest.
It’s important to stay healthy in general in order to stay healthy vocally. There are only a million things to pay attention to in order to do this. It’s certainly beyond me to give advice on such a vast subject as general physical health.
In singing, we need to pay attention to what feels good and what doesn’t. “No pain, no gain” absolutely can’t work in the throat or the rest of the body when it comes to singing.
Singing requires the expenditure of energy and a body and mind that are ready for action. Learning what needs to be activated and what needs to be passive is part of the acquisition of mastery. With study the singer should find singing getting easier. Easy is good. Easy does not mean nothing is happening, that muscles are slack, or that there is no effort whatsoever. The effort expended should invigorate, not strain, and the general experience should be more joyful than sober. If you cannot unequivocally answer the question “Does singing feel good?” with a sure “yes” then something needs to be addressed and corrected.
“Feeling good” should encompass the physical, the mental, and the emotional experience of singing. Singing can feel good long before it is close to perfection! In fact, most people who sing never study, but enjoy it greatly. This is as it should be. It is tragic when vocal study kills the joy. It is the body that tells us first when something is wrong, even while the mind can be in denial. Listen/ feel/ see/ hear, and learn.