Some Tried and True:
~It will focus us.
~What doesn't kill us makes us stronger.
~Its not how far you fall, but how high you bounce back.
Some More Recent:
~Being crushed to the size of a thimble in a Mafia scrap yard and then dropped into a zinc acid bath that once dissolved Jimmy Hoffa focuses your attention.
~Being depatterned at Gitmo and then shot 6000 times by the GAU-8/A Avenger on a Fairchild Republic A-10 Thunderbolt II at close range makes each player take stock of himself and work harder for success.
~When you inhale the contents of a fuel-air bomb, swallow a lit kitchen match, and incinerate from the inside out its a lesson you never forget.
~Nothing teaches like the experience of having an Abrams tank tread rolled back and forth over your head, while a directed energy weapon turns you into a withered stump in front of circus clowns.
(Note: All fiction. No malice.)