Time.  I worry about it during workouts. I mean, they’re only 45 minutes long.  An entire thin-crust supreme pizza wouldn’t last 45 minutes in front of me.  45 minutes is only half the length of a decent movie.  I can piddle away 45 minutes looking for a word in a puzzle.  But put me in a boat with a cramp, or on a bike at the far end of a turnaround ride, or in a car flying down the interstate after  I drank a diet mountain dew?  45 minutes is nearly as long as that insane workout I mentioned earlier.  Seriously.  Do 20 pushups.  That should eat up at least six minutes, don’t you think?  I gotta start working out with people older than me.  They have a better sense of time.