At 57 y/o I don't move like I used to. Runner's High? In the zone? Peak Experiences? Euphoria? Call them what you want. I do know that once on a fairly short 25 mile ride around the June Lake Loop in the Eastern Sierra, I had my most recent peak experience. I became lost in the experience of nature and grand vistas.
I find huge efforts on the bike exhaust me and dull my senses, not enhance them. Suffering on the bike does not bring me euphoria, but the setting I am in seems to be the ticket.