Here is good advice from Grossman on having your mind right before the fight ever begins. That in bold of his quote I believe in highly.
Who decides how much force the warrior has to use? Who ultimately makes the decision that deadly force is needed? The suspect does. The enemy does. The threat does. He fights, you fight. When he uses deadly force, you use deadly force. He makes that decision for you. He has the option to surrender, and your job is to respond with what society says is your right and responsibility to do.
This is why it is paramount that you resolve in your mind whether you can do
it ahead of time. Only when you know you can respond will you have the
ability to truly deter people. That is the great paradox of combat: If you
are truly prepared to kill someone, you are less likely to have to do it.
That person will look into your eyes and see the steely determination to kill
him, and be less eager to attack and more likely to surrender. Lt. Col. Dave