I think it's important to simulate the same ferocity and cold heart in training that you will need when you are fighting. its also important to build your heart when sparring by not being a poos.

you should always go to the attack against one. against multples, stand your ground against two, be allowed to move your foot (pivot) against three and retreat maneuver against four. this should be done from time to time with the intent to develop your 'balls' lol.