I think it's important to be able to laugh at yourself.
The best weapon against an enemy is another enemy.
Efficiency is highly overrated; Goofing off is highly underrated. Regularly scheduled sabbaths, sabbaticals, vacations, breaks, aimless walks and time off are essential for top performance of any kind. The best work ethic requires a good rest ethic.
The old believe everything, the middle-aged suspect everything, the young know everything.
Only those who will risk going too far can possibly find out how far one can go.