It became common some years ago for professional athletes to use sports psychologists to help them perform better on the field. There was a Major League baseball pitcher who had problems getting batters out in pressure situations. He used a psychologist to help him, and one the things the psychologist told him to do was to visualize himself being successful before he ever got to the mound to pitch.
The pitcher really turned his career around after that, and he said the help he got from the psychologist was the biggest reason he was able to do it. He always had the talent and ability, but mentally he was stuck. If you think you are going to fail at something then you have already set yourself up for failure.