Another important aspect of preparation involves "breathing". An important adage related to singing is:As the breath goes, so goes the tone!
Some voice teachers spend a lot of time talking about "singing on the breath." That is, as you sing, concentrate on the air that is coming out of the mouth during the singing process.
As you sing – that is, when your vocal ‘chords’, or ‘folds’ vibrate – you create a column of air that the ear interprets as a particular "pitch." It’s important to also state that the size (not speed) of the air column determines the "volume" of the tone.
The air that causes the vocal chords to vibrate comes, of course, from the lungs. The air from the lungs is a result of the action of the "infamous" diaphragm – a "thin, inner-tube-like muscle" that surrounds the midsection.
It is a large muscle that is constantly in use – without it, we all would die. But the size of the diaphragm-movement required in singing is significantly greater than in normal breathing. Therefore, it requires much greater energy for singing than for speaking! In addition, there are several abdominal muscles located just below the diaphragm that are also involved in the breathing process.
Breathing, then, is just as vital to the singing process as the vocal chords. As you sing or "warm up", in preparation for singing in the choir, you are exercising all of the muscles involved in the breathing process. In the long run, this is just as important to singing as using your vocal chords. And it is why standing or ‘sitting correctly’ is absolutely necessary to great singing!