After years of studying high achievers across diverse fields, top psychologist Angela Duckworth has identified what she calls the most reliable predictor of success—and it challenges conventional wisdom about talent and intelligence. Author Mel Robbins, who has 4.6 million subscribers on YouTube, recently asked Duckworth about her findings during a recording of her podcast, released Monday.

“The common denominator of high achievers, no matter what they’re achieving, is this special combination of passion and perseverance for really long-term goals,” Duckworth explains. “And in a word, it’s grit.”

Duckworth, a professor at the University of Pennsylvania and MacArthur Fellow, defines grit as two interconnected components that work together over time. “It’s these two parts, right? Passion for long-term goals, like loving something and staying in love with it. Not kind of wandering off and doing something else, and then something else again, and then something else again, but having a kind of North Star,” she said.

The perseverance component is equally crucial, according to Duckworth. “Partly, it’s hard work, right? Partly it’s practicing what you can’t yet do, and partly it’s resilience. So part of perseverance is, on the really bad days, do you get up again?”

In children or West Point cadets, research shows grit matters most

Duckworth’s research, which dates back to 2007, has pushed the idea that grit outperforms traditional predictors of success. She studied over 11,000 cadets across multiple years at the U.S. Military Academy at West Point, measuring their “grit scores” upon entry and tracking their performance through the notoriously difficult “Beast Barracks” training program.

The results were striking: Grit proved to be the strongest predictor of which cadets would complete the grueling six-week program, outperforming SAT scores, high school GPA, physical fitness assessments, and even West Point’s comprehensive “Whole Candidate Score.” While 3% of new cadets typically leave during Beast Barracks, those with higher grit scores were significantly more likely to persist.

The academy’s traditional metrics failed to capture what mattered most: the ability to persist when facing extreme challenges.

Similar patterns emerged in Duckworth’s study of National Spelling Bee contestants. Children with higher grit scores were more likely to advance to later rounds of competition, regardless of their measured intelligence. The research showed that gritty spellers engaged more frequently in what researchers call “deliberate practice”: the effortful, often unenjoyable work of studying and memorizing words alone, rather than more pleasant activities like being quizzed by others.

The effort equation

Duckworth’s research revealed a counterintuitive relationship between grit and traditional measures of ability. “I think that absolutely anything that any psychologist tells you is a good thing to have is partly under control,” she told Robbins during the podcast. “I am not saying there aren’t genes that are at play, because every psychologist will tell you that that’s also part of the story for everything—grit included. But you know, how gritty we are is very much a function of what we know, who we’re around, and the places we go.”

In one study, Duckworth found smarter students actually had less grit than their peers who scored lower on intelligence tests. This finding suggests that individuals who aren’t naturally gifted often compensate by working harder and with greater determination—and their effort pays off. At an Ivy League university, the grittiest students, not the smartest ones, achieved the highest GPAs.

Duckworth believes “effort counts twice” in the achievement equation. Her formula is as follows: Talent × Effort = Skill, and Skill × Effort = Achievement.

“Talent is how quickly your skills improve when you invest effort. Achievement is what happens when you take your acquired skills and use them,” she told Forbes in 2017.

An important caveat: Grit isn’t everything

Duckworth’s work has influenced educational policy discussions and military training programs, though she has evolved her thinking about the trait’s role. In 2018, she acknowledged during an interview with EdSurge that “when we are talking about what kids need to grow up and live lives that are happy and healthy and good for other people, it’s a long list of things. Grit is on that list, but it is not the only thing on the list.”

Recent studies have both supported and refined Duckworth’s findings. A 2019 study of West Point cadets, which Duckworth also contributed to, found that while grit remained a significant predictor of graduation, cognitive ability was the strongest predictor of academic and military performance. Other research has questioned whether grit adds substantial predictive power beyond established personality traits like conscientiousness.

Despite ongoing scholarly debate about grit’s uniqueness as a construct, the core insight remains compelling: Sustained effort and commitment to long-term goals often matter more than natural ability alone. As Duckworth put it back in 2017, “Our potential is one thing. What we do with it is quite another.”