Self discipline a better predictor of grades than IQ …
Crack that whip, people. 
From a 2004 study by Martin Seligman and Angela Duckworth done with American 8th graders…
Self-discipline … accounted for more than twice as much variance as IQ in final grades, high school selection, school attendance, hours spent doing homework, hours spent watching television (inversely), and the time of day students began their homework. The effect of self-discipline on final grades held even when controlling for first-marking-period grades, achievement-test scores, and measured IQ. These findings suggest a major reason for students falling short of their intellectual potential: their failure to exercise self-discipline.
