One of the strong influences on health is that of purifying the blood
in the lungs. Plenty of fresh air is necessary for this purifying, and
insufficient or impure air supply in the lungs will send the blood back
to the heart only partially cleansed.
Teach the child to stand erect, to consider his position when sitting,
and at all times to demand fresh air. Do not be afraid of an open
window, always have good ventilation, especially in sleeping rooms.
Give the child a simple exercise for deep breathing and help him to
use it until he has formed the habit of taking several deep breaths of
fresh air immediately upon arising in the morning; each time he goes
out of a building into the open air; and many times during the day.
Singing, running, skipping, jumping rope, etc., are all good exercises
to stimulate deep breathing. See to it that the child breathes through
the nose.