Why not do your best?

In his autobiography Why Not the Best? President Jimmy Carter tells about his interview with Admiral Hyman Rickover, the father of the nuclear Navy, who served on active duty until he was 83 years old. Admiral Rickover personally interviewed every prospective nuclear officer and he made the interviews tough on the novice officers.

When President Carter had his interview, the Admiral asked him what his standing was in his graduating class at the Naval Academy. President Carter said "I swelled my chest with pride and answered, sir, I stood 59th in a class of 820!" and then I sat back to wait for the congratulations.

Instead of congratulations, the Admiral asked, "Did you do your best?" President Carter said he started to answer, "Yes sir," but he thought about who he was talking to, gulped, and admitted, "No sir, I didn’t always do my best." President Carter said the Admiral just looked at him for the longest time and then asked only one more question, which the President said he has never been able to forget, and which he was never able to answer—the Admiral asked, "Why not?"