Breathing is the most intimate possible relationship with the atmosphere — a continuous exchange of molecules between self and world, so intimate that the boundary between them is more conceptual than real. To breathe consciously outdoors is to be reminded, roughly once per second, that you are not separate from the world but a part of it that happens to be ambulatory. Nasreddin breathed the same air as his donkey, the same air as the hills, and considered this not a metaphor but a fact worth meditating on.
Each step builds on the last.