Speaking of preparation and
training. The morning after a shootout between a drunk with a gun and 3 of our finest in which 18 shots were fired and none of them hit the drunk, the Chief of Police was having coffee with our group and tried to explain how this could happen. He showed us that when your hand is trembling really bad, you tend to miss what you are shooting at..
IMO, the mental preparation is more important than the physical. You are going to be within 10', your biggest problem is not killing them, but wounding them and getting sued.
I read somewhere that you have 3/4 of a seconds advantage on a guy that has a gun pointed at you, because you have already decided to shoot him and he hasn't.
When a friend of mine's brother an off duty Sheriff shot and killed a guy trying to hold up someone. His mother was on TV saying that the only reason that he was robbing the guy was to get money for college.