When faced with a particularly difficult decision, Alastair Mitchell Mitchell uses the “big red bus test.” He thinks about walking out of his building in London and crossing the street, only to turn and see that one of those monstrous London double-decker red buses is literally about to flatten him and send him to the hereafter. In the brief instant before the bus hits him, he wonders what would be the thing that he would most regret not having accomplished. The answer to this question should guide prioritization of the efforts of a successful chief executive officer, businessman, or (presumably) ophthalmologist.