But it's about more than the fun factor. For me there is great satisfaction in being able to make that "will I fit through this?" judgment correctly, quickly and with reasonable confidence - something that would have been out of the question a couple of years ago.
I've always had problems with proprioception (awareness of the body in space), and in turn, with spatial rotation. I'm the sort of person who routinely bumps into furniture. Who tries to kick a ball and misses. Who ducks for a tree branch that hangs nowhere near low enough to hit my head. Driving a car was always stressful because of this; the detached, abstracted feel of being inside a vehicle distorted my sense of movement in space even further.
There is a unique physicality to being on a bike, that communicates balance, motion and speed in a way that, however slowly, gets through to me. And it is doing more than teaching me new skills. Essentially it is repairing sensory motor deficiencies that I thought were permanent. It is a gradual process, not a quick fix. But year by year, and sometimes even month by month, the improvements are noticeable. Ironically, I would even feel more confident driving after these years of riding a bike.
There are times I think life is complicated. But then I fly through a gap in a fence without breaking stride and feel so happy, that I remember it is not that complicated after all.