The document discusses grit, which is the ability to withstand stress and persevere through failures to achieve long-term goals, as being a better predictor of success than intelligence. It references a study by psychologist Angela Duckworth that found grit was more important than IQ scores in determining the best performing students. While some high achievers did not have exceptionally high IQs, some intelligent students were not as successful. Grit entails persisting through challenges and setbacks to accomplish something difficult.