relaxing the nervous system

When I was a Buddhist monk I talked a lot about "calming the mind". It's a great thing to talk about! But for a lot of people it sounds great but... it's a bit airy-fairy. Years later when I was running mindfulness sessions at a Rehab Centre I found a way to explain it that people got instantly: I spoke about having a relaxed nervous system.
For modern people those words are much easier to grasp. We all know what it is to have a nervous system that isn't calm! Stress, anxiety, depression, overwhelm: these are the signs that our nervous system is not coping with challenges. I used to guide people through some simple calming techniques such as a simple breathing meditation, and then ask them to notice what it feels like as their nervous system relaxed. Everyone got it. 
So I use both "calming the mind" and "relaxing the nervous system" as ways of encouraging people to focus on what's happening inside them and doing something positive about it.