> First, no, anxiety is not in your body. Fear, just like any other emotion is in your brain. You might get physiological responses in the form of chemicals in your body. That is an effect, not a cause.

Do you have a source for this? I remember seeing an article on (I think) HN about research indicating gut bacteria influences emotions which would seem to me to indicate cause rather than effect. Perhaps it’s impossible to definitively say either way. I can certainly see anxiety being the sort of thing where a feedback loop spirals out of control.