I believe Dr Maxwell Maltz brought up a very important issue, and that is, subtly as I view it, (paraphrasing) How To Fight The Enemy That Lives Between Our Own Two Ears! as expressed in the following astute observations of his:

“One of the reasons it has seemed so difficult for a person to change his habits, his personality, or his way of life, has been that heretofore nearly all efforts at change have been directed to the circumference of the self, so to speak, rather than to the center.”

“Nothing splendid has ever been achieved except by those who dared believe that something inside them was superior to circumstance.

— (quoting) Bruce Barton."

Dr Maltz's view is nonetheless reinforced by other competent observers, as captured below: