This is a great read on the nervous system and especially breathe and the vagus nerve.
I liked this idea that we have something like a secret piano key, under our skin, to press internally to calm us down. Or like a musical string to pluck. At this point I was envisioning the vagus nerve as a single inner cord, stretching from the head to the stomach. In reality, the vagus nerve is a squiggly, shaggy, branching nerve connecting most of the major organs between the brain and colon, like a system of roots or cables. It is the longest nerve in the body, and technically it comes as a pair of two vagus nerves, one for the right side of the body and one for the left. It’s called “vagus” because it wanders, like a vagrant, among the organs.Edith Zimmerman, The Cut