Many people use anger as their fighting spirit but this is dangerous since anger stifles control and thought. A person fighting with pure anger is easier to beat than a person that is fighting using wits. Your fighting spirit should be your will to survive. Control your anger and you will have the edge. Controlled fighting means you minimize your own hurt while maximizing the attacker's hurt. After a fight, a person may not remember how much they hurt you, but they will remember how much you hurt them.
If you have done everything you can do avoid a fight, then there should be no regrets after a fight. A person that has picked a fight, ignored every warning you gave, will not let you back down, and has instigated aggressions, deserves whatever happens. Just remember that the law requires you to use only the force necessary to end the attack.
Fights start for myriad of reasons, some legal, and some illegal. However, for whatever the reason fights start, they all have some common features.
The winner will usually be the first to act
The first to land a good punch will probably be the one to win the fight. As explained in the "First-Strike" item, traditionally there is no first strike in Taekwondo. However, in a fight, you can never allow your attacker to gain the advantage. You must take control of the situation and not merely react to the attacker's actions.