From The Art and Popular Culture Encyclopedia
Discipline denotes any training intended to develop moral character, or produce a pattern of behaviour. "Discipline" in this context, while often thought to be a coercive mechanism, can be a collaborative process of building consensus regarding accepted behavior within institutions and society.
Self-discipline is the ability to exercise control over one's behaviour or emotions (see self control and willpower). Self-discipline is to some extent a substitute for motivation, when one uses reason to determine a best course of action that opposes one's desires. Lord Alfred Tennyson commented on self-discipline in this way: "Self-reverence, self-knowledge, self-control. These three alone lead to sovereign power", with"sovereign power meaning self-discipline.
Self-discipline can be viewed as the ability to motivate oneself in spite of a negative emotional state. Qualities associated with self-discipline include willpower, hard work, and persistence.
Self-discipline is the product of persisted willpower. Whereas willpower is the strength and ability to carryout a certain task, self-discipline is the ability to use it routinely and even automatically (as if through reflex). An analogy for the relationship between the two might be defined as follows: Where willpower is the muscle, self-discipline is the structured thought that controls that muscle. In most cultures, it has been noted that self-discipline is the ultimate path towards success.