Self-Control is important, and teachable to some extent

Self-control or behavioral disinhibition has been implicated in a number of psychiatric disorders, including Attention-Deficit/Hyperactivity Disorder (ADHD). It may be a mediating factor responsible for the lowered academic performance found among many children with ADHD.
The ability to inhibit responses may predict academic performance even better than IQ. This New Yorker article reviews studies of self-regulation and how “will power” may be a trainable trait that makes a difference in our social, academic, and financial domains.