Exactly, perception is reality. Far too many people – in all areas of life, not just in running or sports – unfortunately sell themselves short. This is why it is so important to surround oneself with an effective support system.
I do not believe that is the point of the article. The point of the article is that you must have a commitment to excel in order to excel. You cannot make that commitment until you accept that you will excel.
“We are what we repeatedly do. Excellence, then, is not an act, but a habit.” to quote Aristotle might be a better summary.