When I'm working on a problem I'm having trouble with, I'll often get up and slowly pace across the room whilst kicking a ping pong ball around or throwing a ball up in the air and catching it. It feels like I can think more clearly when doing this. It's as if my doing this repetitive activity allows me to turn my focus off the rest of the external world and focus on this simple activity. It's like I can tune out the cars rumble by outside, the music, the refrigerator buzz, the television, the family members talking, the occasional itch, etc. by focusing my attention; and it allows me to put more of my attention to the problem I'm thinking about without all those other things bombarding me. Does anyone else do this? Maybe I have ADD? Maybe I've had too much coffee? What do you do when you think? How do you focus?