Because the demands on a goalie are mostly mental, it means...

Because the demands on a goalie are mostly mental, it means that for a goalie the biggest enemy is himself. Not a puck, not an opponent, not a quirk of size or style. Him. The stress and anxiety he feels when he plays, the fear of failing, the fear of being embarrassed, the fear of being physically hurt, all the symptoms of his position, in constant ebb and flow, but never disappearing. The successful goalie understands these neuroses, accepts them, and puts them under control. The unsuccessful goalie is distracted by them, his mind in knots, his body quickly following.