Life at 40 heartbeats per minute is very different from life at 140 (and higher); and both are better, I think, than life in between.
I wrote a lot of things that basically approximate an English grad's attempt at science words but deleted them because ultimately this is not a science-grounded observation I am trying to make.
It occurs to me during nearly every run - and especially so during harder efforts - that there is a greater sense of place and lucidity which is difficult to put into words. It is the sort of thing that you can only communicate to others who know, those who do not need to be told - except, perhaps, to validate our shared insanity.
I wrote some pop psychology stuff here but deleted it too. Words are tools and I am hammering my fingers trying to use them.
If you've ever read any literature on the theory or practice of meditation I would simply say that it is like that. You are privy, as often as you choose, to a glimpse of something that feels like true experience. Better, even, is the sense of peace and lack of anxiety that permeates through the day's other waking moments.
And while I deleted all my attempts at garbling the scientific mechanisms behind these phenomena, they are both measurable and real.
Someone gave me a banana today and I was fucking stoked.