When not singing, speaking or practising an exercise that demands it, _keep your mouth shut_.
ATTITUDE Dress the neck and body loosely, so as to give the throat and trunk perfect freedom.

Place the hands on the hips, so as to free the chest from the weight of the arms.

Stand erect, evenly upon the balls of the feet; the body straight, but not strained.

Raise the back of the head slightly without bending the neck.

This action will straighten the spine, place the chest forward, and bring the abdomen backward into its proper relation.
The great majority of people are shallow breathers, chest breathers, who when told to take a "deep breath" do not know what is meant.