Self-disciplined (自律的) people are not all excellent people. But nearly all excellent people are self-disciplined people. Some of them read every day. Some of them never run late. The real difference between an elite person and an ordinary(普通的) person is that an elite person can manage his or her time well. That's where their success comes from. What people call self-discipline is in fact self-management.
One example is staying fit. Never underestimate (低估) someone who is in good shape(身材). Anyone who has ever tried to lose weight knows that it's not easy. It's even harder to avoid putting weight back on. If someone is in good shape, it shows that he knows the principles (原则) of staying fit and is able to stick to a plan that uses these principles.
If someone is in good shape, it means that this person is good at managing themselves and their time. Whether it is natural or acquired, it is a great skill. It also shows that this person is able to keep persevering (坚定不移的) and can balance long-term goals with short-term goals. So if someone is in good shape, he or she is way more than just healthy.
How do you learn self-management? First of all, set a goal and write down your reasons for wanting to achieve it. Create a list of all the things you need to do to achieve this goal and start to work on them one at a time. With self-discipline, small things in life will no longer trouble you. Only through self-discipline can you truly own your future.