Breathing is one internal function that the conscious mind can control with comparative ease. The effect of controlled breathing is almost like communication with all conscious parts of one's being saying to them, "Simmer down and listen; there is something beyond the turmoil". It is communication in action that often works when words merely go in one ear and out the other, not even changing the cognitive mind. In essence, the effect is to turn all the elements of our will toward stillness and waiting.
Breath of life,
You ride the waves of life with me
in the rhythms of my communion with you.
You enter the comings and goings
of each day and in every prayer I breathe.
Whether I am in the stillness of quiet prayer
or in the fullness of the day's activity,
may your peace flow through my being.