To think good thoughts requires effort. This is one of the things that discipline – training – is about.
In its natural sense, discipline is systematic instruction intended to train a person, sometimes literally called a disciple, in a craft, trade or other activity, or to follow a particular code of conduct or "order". Often, the phrase "to discipline" carries a negative connotation. This is the case because enforcement of order is often regulated through the threat of punishment to ensure given instructions are carried out.
Discipline is the assertion of willpower over more base desires, and is usually understood to be synonymous with self control. Self-discipline is to some extent a substitute for motivation, when one uses reason to determine the best course of action that opposes one's desires. Virtuous behavior is when one's motivations are aligned with one's reasoned aims: to do what one knows is best and to do it gladly. Continent behavior, on the other hand, is when one does what one knows is best, but must do it by opposing one's motivations. Moving from continent to virtuous behavior requires training and some self-discipline.
The regulation of the behaviors of members of any military, involving rules that govern goal orientation and behavior inside and outside the institution, including the socialization processes that happen in military training. Rules of discipline are firmer or laxer depending on the prevalent culture of the military's country or institution. As early as the time of the Roman Army, discipline was enforced through military justice, but broader compilations of laws such as the Codex Theodosianus contained provisions dealing with military discipline.
Prison discipline refers to the means by which prison staff maintain order inside prisons and correctional facilities as well as the state of order as such. This is ususally enforced through different forms of punishments, such as solitary confinement, exclusion from certain prison programs, revocation of priviliges and forfeiture of good conduct time. In the past, prisons predominantly used corporal punishment on inmates who violated prison rules, which is still employed to maintain and enforce prison discipline in a number or countries to the present day.