When I think about walking, a word that now comes to mind is “deliberate.” I have to plan every step I take; no extraneous side trips or wasted effort. I have to think about the way I sit in a chair: Am I settled in the right way? I do an inventory of where my limbs are. All of this calculation and deliberation is rigorous work. Physical tasks are made more difficult by the need to break them down into all of their components.