While enthusiasm is the vital quality that arouses one to action, self control is the guide that directs your actions and energies constructively. Here are a few thoughts on how to exercise self control to constructive ends:
1) Self Control is solely a matter of Thought Control. Control over your thoughts is really the only thing that we have absolute control over. The most powerful form of self control is to keep the sort of thoughts in your mind that you desire, and keep out the thoughts that you don't. What defines who we are and what will ultimately determine what we accomplish is based on the sum total of our dominating thoughts.
2) All successful people exercise self control with their thoughts, words, and actions. Failures, on the other hand, let their thoughts, words, and actions run wild. A person with self control does not indulge in destructive emotions such as hatred, envy, jealously, fear, or revenge. All of these destructive emotions carry toxic thoughts with them. A person with self control will never, under any circumstance, slander another person or hate those that disagree with them.
3) A person of self control is self aware enough to know that sometimes they are wrong. Rather than hate the accuser, they will endeavor to understand the reason for the disagreement and learn from it. Admitting a mistake allows one to profit from it, while defending it ensures that you will learn nothing and will likely make the same mistake again.
4) There is an old saying, "Whom the gods would destroy, they first make mad." This is why the oldest trick in the book for a trial lawyer is to make the witness angry, in hopes that they will blurt out the information they are looking for in a rage. No one can control or influence others if he can't control themselves. No matter what the circumstance, he who keeps his cool will always control the situation.
Viktor Frankl was an Austrian holocaust survivor. He is best known for having complete self control over his mind and thoughts while going through an unimaginable experience. He said, "The one thing that you cannot take away from me is the way I choose to respond to what you do to me. The last of one's freedom is to choose one's attitude in any given circumstance." At first his happiness while being tortured made the guards angry, but he quickly won them over once they realized that there was nothing they could do to affect him. Exercising his right to the last freedom of self control over mind and thought allowed him to control the situation and ultimately led to his freedom.