This one is hard to leave unanswered, so I'll take a stab. I like where riding puts my mind, especially mountain biking - I love to ride road from time to time, but it takes me a while to shut out the day on a road bike and I have to worry about mindless motorists, It's like driving without the benefit of protection.
On single track I feel my complete attention is required to what I am riding and the worries of the day are gone in the first 100 feet of trail.
I've done a bit of trail maintenance, some organized and some rogue (nothing crazy, just patching) and I have to say I love trails, the people that build and maintain them, and the people that use them (maybe even the occasional jerk who seems oblivious to etiquette).
I like the activity and I've found I generally like the people who ride. I've moved around a bit in life and the ride has generally been the spark for some great friendships. I know it has been a strong thread in my marriage and I'm grateful for that.
Even though I don't "train" and too often let crap keep me from the bike, I see it as essential to me. To paraphrase and cheese up Descartes "I am, therefor I ride."
