Much of Sun Tzu's effort in preventing war is to focus on the emotional state, namely anger. With great wisdom and humaneness, he said, "Those angry will be happy again, and those wrathful will be cheerful again, but a destroyed nation cannot exist again, the dead cannot be brought back to life."
According to Sun Tzu, anger is also one of the five dangerous traits of a general. He said, "He who is quick tempered can be insulted." When you are easily insulted, you are much more likely to make rash, illogical, and harmful decisions. You may think you can use this on the enemy, but a far greater enemy is within you, who can do much greater harm. Observe, prepare, and protect yourself.
Here are some ways to reduce the anger in your life:
(1) Make being calm a habit. That is to say, create a good habit to subvert a bad habit. Make every situation a test, a challenge. Record down your progress every day. Note the times when you got upset. Visualize what could you have done different. Be ready next time.
(2) Stay away from things or people who make you angry. You can walk a thousand miles and be completely safe, yet others can encounter danger in the first mile. That is because you aren't careless and don't take paths that are dangerous.
(3) Find out what calms you down. When were the times you were able to catch yourself and you made a good decision despite being angry initially? Was it music? Was it taking a walk? Was it remembering the good aspects of the person or of life? Employ that every time you get upset.
(4) Confront head on things or people who make you angry. This is the opposite of #2. Do this only after you have #1 and #3 down pat and are ready and prepared for #4. Once you are able to overcome #4, then you have overcome and mastered the one enemy that even many leaders of great nations cannot do.