I've written about the breathing thing being voluntary and involuntary for years. I consider it more linking your conscious mind to your unconscious mind more than to mystical realms, but that's just me. Your conscious mind is more word oriented, so what can help with connecting your conscious mind to your unconscious mind is associating words with your breathing. For me, an inhale is "oh" and exhale is "ho". The words don't need to be verbalized but that helps.

When bicycling or doing other aerobic activities, it is usually your lungs that go first, but not if you have trained your breathing. As a diver, I know that breath control can save you when you are at the extreme limit.