Pain is a function of the body's nervous system - nothing more. It lets us know when our bodies are being injured. In a fight, we expect our body to be injured. Though it is certainly possible to win a fight without sustaining injury, it would be unwise to assume that to be the case. Since we are essentially planning to be injured during the course of the fight, pain serves no purpose. It becomes functionally irrelevant. Either ignore it totally, or use it to drive your ferocity. If you sustain serious injury, do everything you can to continue to concentrate on the fight. This is terribly difficult, but not impossible. Don't focus your attention on injuries. Think about winning the fight. There will be time later to heal - if you survive the fight.

Just as pain is merely a function of the nerves, fear is simply an emotion. It can be harnessed, controlled, and directed. Never consider what a big, strong, violently deranged opponent you are up against. This is self-defeating. You will lose. Instead, throw yourself into the "process" of fighting. Think of the opponent as a target system for you to systematically evaluate, analyze, and destroy. That person exists for you to damage. Do it!

In a fight, fear is a big factor only if you let it be.  Take firm control of your emotions, and force yourself into what a friend of mine calls "terminator mode". Your job is to take that guy down.  Transform the fear into ferocity, and systematically use your fighting attributes more effectively than he is using his. It's irrelevant that he might be very big and strong.  It's irrelevant that you might be very afraid.  Your mission is to deal in reality.  Take him down! There is nothing wrong with fear. Just don't let it get in the way. It's just an emotion.