If a Bird Can't Fly, It Walks.
"If A Bird Can't Fly, It Walks" is intended to be used when someone should stop making excuses for why they can't do something. I think what I like most about it is that it's handy advice that is sometimes conveyed rather harshly. I think this little gem provides handy advice dispensed in a gentle fashion. It's truly brilliant.
The above illustration, drawn by Kevin himself, is in a sticker form suitable for, as the Morning News puts it, "display on the tail of your crapped-out Corolla, on the wall of your cube at your hopeless job, or above your workbench at home, where the real work is done."