Ford isn't merely praising positive thinking—he's describing a peculiar trap where our beliefs become self-fulfilling prophecies through invisible mechanisms we don't consciously recognize. A person convinced they'll fail at public speaking unconsciously speaks faster, makes less eye contact, and interprets neutral audience reactions as confirmation of their inadequacy, while the believer in their own capability mistakes their own nervousness for useful adrenaline. The real sting of the quote lies in its symmetry: both the confident person and the doubtful person are ultimately *right*, which means doubt doesn't just feel bad—it's also, paradoxically, efficient at proving itself true.