Here's the quote:
Here's the physical analogue:
The metaphorical point being that sitting at our desks making clockwise circles with our right foot is 99.9% of our lives. The remaining .1% is mostly about accepting (or denying) that when we try to draw the number "6" in the air with our hand our foot will change direction and there is nothing we can do about it.
That, as DFW goes on to say:
"...both destiny's kisses and its dope-slaps illustrate an individual person's basic powerlessness over the really meaningful events in his life; i.e. almost nothing important that ever happens to you happens because you engineer it. Destiny has no beeper; destiny always leans trench-coated out of an alley with some sort of Psst that you usually can't even hear because you're in such a rush to or from something important you have tried to engineer".