It isn't possible to achieve self-discipline without making some proGREss on those other principles; self discipline requries self-knowledge and an accurate assesssment of your current abilities. Likewise, the other principles can't really be put into action without self-disciples can't really be put into action without self-discipline. It is the channel through which all your personal power for success must flow.
Think of your mind as a reserveoir in which you have been storing up potential power. You will now learn to release that power in precise quantities and specific directions. This is the essence of self-discipline.
Most people act first and think about the consequesnces later. Self-discipline will reverse that process. You will learn to think before you act.
Self-discipline calls for balancing your emotions with your reasoning. This means you must learn to consult both your fellings and your reason before you reach any decision. Sometimes you will need to set aside（驳回，撤销） your emotions and fllow the dictates of reason alone. Other times you will decide in favor of your emotions, modified by your reson. A happpy medium is imporant.
Consider, for example, those people who are so in love that they will do anything for their beloveds. Thery are putty in the hands of other. They rarely amount to anything because they have no purposes of their own in life.
You might wonder if this danger means that it would be sager and wiser to control your life strictly on the basis of reason and leave emotion out of every decisison. The answer is and emphatic no.
Don't forget, your emotions provide your driving power, the activating force which enables you to put your decisions into action. If you destroyed hope and faith, what would there be to live for? If you killed enthusiasm, loyalty, and desire but still retained reason, what good would reason be? It would still be there to provide direction, but what would it dirct?
You must control and direct your emotions, not abolish（废除） them. Besides, abolition would be animossible task. Emotions are like a river. Theire power can be dammed up and released under control and direction, but is cannot be held forever in check. Sooner or later the dam will burst, unleashing catastrophic destruction.
Your negative emotions can also be controlled and directed. PMA and self-discipline can remove their harmful effects and make them serve constructive purposes. Sometimes fear and anger will inspire intense action. But you must always submit your negative emotions--and you positive ones--to the examination of your reson before releasing the. Emotion without reson is a dreadful enemy.
What faculty provides the crucial balance between emotions and reason? It is your willpower（毅力） , or ego, a subject which will be explored in more detail below. Self-dicipline will teach you to therow your willpower behind either reson or emotion and amplify the intesity of their exprssion.
Both your heart and your mind need a master, and they can find the master in your ego. However, your ego will fill thei role only if you use self-discipline. In the absence of self-dicipline, your mind and heart will fight their battles as they please. In this situation the person within whose mind the fight is carried out often gets badly hurt.1