Who or what has control over you? Self-discipline is defined as the ability to control one's feelings and overcome one's weaknesses; the ability to pursue what one thinks is right despite temptations.
When you make the decision to exercise self discipline in any giver circumstance you are likely better off than giving into the temptation of immediate gratification. The word of God talks about self discipline and encourages us as believers to practice self-control, and to live a discipline life.