Self Image
Each one of us carries within, a picture of ourselves. That picture is our "self image," our conception of the "sort of person I am." It is formed and strengthened from our own Beliefs  about ourselves. Many of these Beliefs have been unconsciously formed from past experiences, failures and successes and the way others have reacted to us, especially in childhood. From this we mentally construct a Self (picture of Self).

Once the idea or belief of ourselves goes into the picture, it becomes, as far as we are personally concerned, "the truth." We do not question it's validity, instead we proceed and act upon it , "just as if it were true."

The Self image controls what you can and cannot accomplish in life, what is difficult or easy for you, and how others respond to you. Your behaviour, actions, feelings and potential success are always consistent with your Self image.
The Self image is a foundation upon which your personality, behaviour, and even circumstances are built. As a result our experiences validate and strengthen our current Self image, which then sets up a vicious or beneficial cycle. You cannot escape your Self image for long. Willpower and conscious effort alone, are unlikely to provide lasting and sustainable change. To sum up, you will "act like" the person you conceive yourself to be.
E.g. If you have a "fat" self image, and find that when you consciously try to lose weight and keep it off using willpower that you may well be working in direct opposition to your current Self image, and therefore become unsuccessful in your endeavours.
Whatever is difficult for you, whatever frustrations in your life, they are likely "proving," and reinforcing something ingrained in your self image. Because of this objective "proof," it seldom occurs that the crux of the trouble rests in the self image, and our valuation of ourselves.
The good news is the Self image can change. Self image management coaching has evolved from well over a decade of my experience of working with clients in the therapy field.