So much THIS.  I've seen it dozens and dozens of times in the military.  Constructive (and sometimes non constructive) criticism, and some serious shit talking can really harden someone mentally and get them to understand that when you fail, it's going to hurt.  You get the fuck back up, get your ass handed to you, find the strength to press on and get the job done.  You either rise to the challenge, or you crawl back into your Mommy's safe space.