Breath is crucial for life. Physical respiration goes on as a largely unconscious process as the body exchanges oxygen and carbon dioxide to power the activities of every cell in our bodies. Deliberate deep breathing will ensure that we take in enough oxygen and can calm feelings of breathlessness or fear. Conscious breathing used as part of a spiritual practice focuses the mind's attention and helps relieve stress on our bodies.
~ from NAVIGATING THE TIDES OF CHANGE by David La Chapelle
And how does one go chasing after a glimpse of the uncreated Light? The Hesychasts, high on Mount Athos, bowed their heads upon their breasts, took a deep breath, and plunged in. What they plunged into was prayer. It began with a tack with which to fix the attention. It became breath itself, an inlet for the universe to invade one's body until the entire cosmos, drawn in, heaved out, was transformed into prayer. The body's posture was important. The breathing was to be carefully controlled so as to keep time with the words. Eventually the prayer, breathed in, united with their very blood and heartbeat; breathed out, it blessed the world. And some monks claimed after a while to have indeed seen the Light of the Transfiguration, uncreated energy beheld by bodily eyes.
~ from AND THE TREES CLAP THEIR HANDS by Virginia Stem Owens