Sometimes when I'm tired or ill, I can get into a state walking home where my legs are on 'automatic', and seem to be disconnected from my brain and the rest of me. I seem to be able to just put the gear stick into drive, and then sit back. It's almost like traveling in a vehicle, or riding on your father's shoulders when you were little, or even wearing a pair of Techno Trousers (ex-NASA!). You can look around, daydream or just generally relax while your legs mechanically eat up the kilometres. Weird.