Breathing is really the only way that we know of, biologically speaking, to deliberately get a handle on your nervous system.
If we do regularly and deeply diaphragmatic breathing, after a couple of minutes, we can slow our heart rates. Basically, it calms our system down to avoid continuous huge emotional expenditure.
Let's follow the instruction below to take a deep breath right now if available.
"Put your hand on your torso or tummy. Don't breathe from your chest, but from your diaphragm. When you breathe in, you don’t want your chest to expand. What you want is your stomach kind of to expand. So breathe in and have your stomach expand. Take in breath down to the bottom of your lungs, instead of just the top. Breath in for three seconds and out for another three."