When running, I find that, as I breathe out, I tend to count. When I reach 50 I reset to 1. This process seems to induce (or be) some kind of trance.
Sometimes I find I have counted to say 65 without noticing.
This suggests that I have come up with a measure for the depth of my running trance state at any time.
ie 65-50 = 15 = depth of the trance. (Or, if you are a pernickity Physicist, we could normalise that by dividing by 50).