There are several synonyms for the phrase "believer in discipline." Some common ones include strict, disciplined, self-controlled, regimented, and structured. Each of these words suggests an individual who values self-discipline, organization, and routine. A strict person often adheres to rules and guidelines, while a disciplined person has developed strong habits of self-control. A self-controlled individual can resist temptations and impulses, while someone who is regimented follows a strict routine. Finally, a structured person implements systems and processes to maintain order and efficiency. Whether you describe yourself as a believer in discipline or use one of these synonyms, these traits can help you achieve success and reach your goals.