At wit's end

Was just thinking about the Rosenthal Effect and how it might relate to my own tutoring. Rosenthal posits that by the sheer magic of willpower, one can spur others to greater heights.

This however appears to be part of the equation. The more important variable isn't addressed. It doesn't account for the determination - or its lack thereof - in students.

Simply wondering what's the mojo that can allow people to reach their aspirations. Why aren't the students scoring despite intense, positive beliefs in them? Is it because they themselves are satisfied with mediocrity? What are the exact ingredients to concoct the cocktail of success?