I find riding a bike to be like playing a video game. I'm an unreformed chatterbox when riding with others, but when riding alone (most of the time) I go into a zen-like state where my mind empties, and all I do is focus on the task at hand ... riding a bike.

And something happens when I do that. It's as if all of the background processing ... things that are floating around in my subconscious mine ... come to the fore. But soon, even they are overwhelmed by the zen.

Kinda strange. I think it is one of the reasons riding a bike is so challenging and relaxing at the same time.