Jogging along yesterday I finally figured out a good name for that special exercise-induced euphoric state: light mindedness. It's a happy mental escape hatch from the counterproductive tension that dominates life in this part of the 21st century world. No time-pressure, no heaviness ... just sensation, immersion in the present moment, plus alert anticipation of what may lie around the next corner. Attentive poise. Grace. Zen.
I went at a comfortably slow pace and set new personal marks in distance (~15 miles) and duration (~3 hours) for an outing. And when I was done I felt pleasantly foolish in my pride, the way Samuel Pepys once said he felt about his new pocket watch, and the way I felt six months ago when I first managed to run ~10% of that distance without collapsing.
Twenty years ago CS, a senior colleague, politely asked me to stop finishing his sentences for him. "Slow down," he advised. "This job isn't a sprint, it's a marathon.". CS is now retired from a successful career and spends his time enjoying his grandchildren. He was light minded. May we all be so wise.