craig, I think you and I are are in the same place. It is mental, but also spiritual. In my opinion, for my case specifically, my body is stressed out and weak from being anxious all the time... about something.....
I need to face something.... in my mind... in an extreme way. I need to face my worst fear and call it what it is. Then my body will relax and recover naturally.
I was told this stuff by somebody who did 10+ years of psychotherapy and 20 years of meditation and he did this specific fear confrontation and mentioned it was part of being a spiritual adult, which almost no one alive today is.
I am looking forward to hearing your opinions too, and if you wouldn't mind messaging me your views too that would be cool !