Ten year ago, our SWAT team attended one of Col. Dave Grossman's seminars. It was title, On killing and the Bullet proof Mind. There was a Jewish power lifter as a guest speaker, great guy! He was working (at the time) on the world record in the squat, or maybe the dead lift, not sure, but he was also a police psychologist. Something he taught us has stayed with me all these years. He said that every time we talk our selves out of the workout we had planed for any particular day, we were creating neurotransmitters in our brain that would prevent us from continuing on in the fight should we be pushed past our level of mental toughness we had previously brought ourselves to. He said that we develop the never quit mindset when we train ourselves on an individual level. Every time we drag ourselves to train on days when we just don't feel like it, or we are just plain feeling lazy, we develop in ourselves a mental toughness that will keep us in the fight on game day.

He said that he had interviewed hundreds of police officers that were down on the ground fighting for their lives either from GSW's, or some perk on top of them beating their head in with a rock, and of those that survived, he found the common denominator to be a commitment to train, even when they did not feel like it.

http://www.crossfit.com/mt-archive2/003760.html