From Education Week--According to the latest research, the two best predictors of college success are not grades and intellectual ability. Number one is “conscientiousness” (dependability, perseverance, work ethic). Number two is “agreeableness” (interpersonal skills, getting along with other people, working well in groups).
From what I’ve observed, I would say the same is true for life after college—jobs and careers, marriage and family life. Success comes more easily for people who are willing to work hard and who are able to cooperate with other people.