" The past three decades have witnessed unprecedented growth in what researchers now term ultimate human performance. This is not the same as optimal human performance, and the difference is in the consequences. Optimal performance is about being your best; ultimate performance is about being your best when any mistake could kill. Both common sense and evolutionary biology tell us that progress under these “ultimate” conditions should be a laggard’s game, but that’s not exactly what the data suggests. "

― Steven Kotler , The Rise of Superman: Decoding the Science of Ultimate Human Performance