The Motivation Trifecta: Autonomy, Mastery, and Purpose
Long distance riding certainly provides opportunity for autonomy and mastery. For me, every time I rode a longer brevet I learned I was capable of doing more than I believed; exploring my limits became my purpose. So if this article is to be believed, we ride because long distance riding provides the three keys needed for motivation. Makes sense to me, anyway.
I think that's why in 2012, post PBP, I quit after completing my 400k: I found it pointless. I knew I could ride the distance; there was no mystery and no real new challenge. Starting an R-12 created a new challenge. Since then I've found the challenge of a 24 hour race, and this summer a 1500k.