Man is different from other creatures. He lives in society. So he has to regulate his life. He must observe certain rules of conduct. Discipline means living under strict rules. It means not to break the rules.
Discipline is a must in every walk of life. The student life requires that they should observe school discipline. He should come to his class punctual. He should obey his teachers. He should always speak truth. He should not misbehave with his teachers. The military requires discipline, there is not to reason why. There is rule to obey the order. When a soldier receives order from his senior he should obey it without questioning.
There is also religious discipline. In every religion one has to observe the religious ceremonies according to the set rules. While presenting in a temple we are not to laugh.
In Short Discipline makes us better person. We get respect from our fellowman.