Here are some nice reasons why this habit helps:
1. Punctuality is the first thing that teachers, be it in school or college, or the seniors at work, or even colleagues, always acknowledge and appreciate.
2. It reassures people by giving an implicit positive assurance about your sincerity and capability.
3. It presents you with an image of reliability and politeness, and they trust you better.
4. "It talks volumes about being professional in attitude when it comes to work"- as a senior at work told me once.
5. The truth is that when you have this habit ingrained, you do not even have to try to be professional! In fact, I go on time for work, or when I promise to a friend. And, there is no difference I see between the two situations.
6. It just becomes a part of your very identity, and that gives you a lot of confidence!
7. Finally, being on time shows how much you respect your time, and their time. It shows that you don't take the other person and their time for granted. And, it shows that you value your time, too.
Being on time is something indispensable for me. It has always been a habit ingrained into us at home. We had never gone even a minute late to school, all through our school life. I can never knowingly walk late into the class, or be fine with the delay of submission of a project beyond the time mentioned(even if it has absolutely zero consequences). If I tell a friend I'll meet them in 10 minutes, I am ready and waiting for them by the 8th minute.
But, you can't be punctual all the time. It happens even to me. Sometimes, you just cannot avoid a delay, try as hard as you want. In those times, what we need to do, but fail to do, is to communicate. All we need to do is let the other person know that we are running late, and give them a time frame to look forward to. Leaving someone hanging without any communication is what makes a delay really hard to put up with.
Moral of the story: Being on time is better than being in time. But, being in time, or on time, is better than being late. But again, being late on communication is better than no communication. Happy day!