GRATITUDE is a choice that becomes a habit. It is a major ingredient in the alchemy of transformation and is closely related to love... Gratitude creates a combustion of energy that powers our living cells. That's why all spiritual traditions teach the importance of gratitude. It certainly isn't because the deity needs any reassurance. Rather it's because when we are in the state of gratitude, we're affirming our faith in our own highest good and denying authority to the paralyzing, constricting energy of fear.
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.