1. How "gritty" they are

We say some people are "mentally tough" or "gritty" as if these were mere personality traits. But UPenn psychologist Angela Duckworth has found that stick-with-it quality to be vitally important in accomplishing goals.

Duckworth's research has found the kids who do the best in life learn how to cultivate this skill of resilience.

In short, they know how to get back up after they fail.