When you do what you have promised, people see you as a responsible and reliable person. This is quite admirable, as many people won’t deal with individuals who are irresponsible.
They will give their trust to friends they can count on, and give their business to companies they admire. A responsible person is one who can be trusted to act without needing strict supervision, because they are accountable for their own behavior. Keep doing it, and you’ll soon develop a reputation for following through on obligations.