If you are in the dark, it does not mean that you have failed and that you have taken some terrible misstep. For many years I thought my questions and my doubt and my sense of God's absence were all signs of my lack of faith, but now I know this is the way the life of the spirit goes.
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.