Generally speaking, the basic importance of discipline is to obey consistently. Most of the time that value comes with a price, which is rejection and suppression of seductions and passions. This is why discipline, while highly important, can also be very hard for those who lack it.
The art of discipline expresses itself in various of ways. whether by obeying the current authority, or pursuing a goal in solitude. One can say discipline comes into practice when a kid becomes a student in school. He has to obey his teachers, do his homework and follow the rules of the institution. The more the kid obeys and does his obligations, the better disciplined he or she becomes. Thus on the interpersonal level, discipline serves a basic function in a social order or construct. The better the members of a certain construct are discipline, the more productive and efficient the construct is.
As already said, discipline also serves a role in solitude, and because it is not necessarily dependent on other people, it is called self-discipline. Self discipline is the ability of obeying oneself persistently at the price of avoiding pleasure and being lazy. As an individual who very much appreciate self-discipline, I believe it serves as a better motivation than simply a certain urge, and it is very important to maintain, specifically in solitude, because in solitude no one is there to take care of you. Thus, the self-disciplined ought to take care of themselves, whether it is the maintenance of the body, pursuing a hobby or doing a project.
One can say discipline is the exact opposite of laziness, which I believe to be true. The lazy individual is prone to damage their health by pursuing passions which do not require much power and determination, such as playing video games for long periods of time. The lazy person is not discipline because they lack the will of effort to do something which is not fun or grant them pleasure. I tend to believe that children are usually very lazy, mostly today. Instead of indulging in physical exercise, they usually spend their time in front of a computer or a TV screen, and thus some of them get obese and weak. Laziness can be compered to a demon which seduce you to harm yourself and your body by submitting to pleasures instead of effort.
One thing I find most advantageous in discipline is the ability to liberate oneself from current will and overcome it in the name of a higher value or goal, thus making the discipline a master of their own selves in the name of rationality. To be discipline is to know and to exercise the notion that there things more important in life than simply hanging around or slacking. This is why self-discipline is also important when leading a healthy lifestyle of good nutrition and physical exercise. The healthy one overcomes the temptation for candies, cigarettes, alcohol and so forth, and the sportsman overcomes their will to skip a training session.
Discipline is also very vital when growing up mentally, and therefore high levels of it can indicate a mature personality. The mature individual knows that he has obligations, whether to himself or to other people, and he or she is the one to take responsibility over one’s deeds. The discipline knows it too, and therefore they are mature individuals.
An example of self-discipline can be me. I made an obligation to myself to go to the local gym once it two days, regardless if I want it or not or prefer to do something else at a certain moment. Except one time when I skipped gym because of muscle pain, I keep my obligation and plan to do so until the end of my membership. I know that going to the gym is important because it is good for my health and physical maintenance. Thus, being disciplined means to do your deeds not because you want them necessarily, but because you are aware of their functionality whether to yourself or to society.