Take a slow, deep breath. Now take another. What do you notice when you breathe consciously?

I teach a simple exercise to those in palliative care, and those caring for them.

Open your left hand, palm facing outward. Use your pointer finger of the right hand to trace up the outside of your left thumb while breathing in deeply through the nose for the count of five. Hold in this air to count of five at top of thumb. Trace down inside of thumb while breathing out slowly through mouth (relax jaw) to count of five. Follow these patterns for the rest of your fingers. When finished. You can repeat on the other hand if need be.

A great, simple breathing exercise for calming both the nervous system and the overworked mind is a timed breath. 

When your exhale deeply, the vagus nerve (running from the neck down through the diaphragm) sends a signal to your brain to turn up your parasympathetic nervous system and turn down your sympathetic nervous system.

The sympathetic system commands your fight or flight response, and when they fire, your heart rate and your breathing speed up, and stress hormones like cortisol start pumping through your bloodstream, preparing your body to face a threat.

The parasympathetic system, on the other hand, controls your rest, relax, and digest response. When the parasympathetic system is dominant, your breathing slows, your heart rate drops, your blood pressure lowers as the blood vessels relax, and your body is put into a state of calm and healing.