What people believe about themselves and their abilities serves as a self-fulfilling prophecy. Believing oneself to be inferior, untalented, unimportant or incapable influences one’s actual abilities. One’s self-concept greatly determines what one can actually do. If you view yourself as unable to do things, you will be unable to do them. On the other hand, if you see yourself as talented, capable, and important, your self-concept will open up powers and talents that would have remained dormant had you thought of yourself in lesser terms. We have the ability to change our self-concept…. Hardly anyone utilizes their entire capabilities. Most people use a low percentage of their potential, and could accomplish much more than they realize. By deciding you are capable of accomplishing more, you will accomplish more.
From ‘Building your self-image and the self-image of others (Rabbi Pliskin)’