It’s not every day that distinguished Ivy League professors quote Hollywood actors in their epigraphs. But that’s exactly what Angela Duckworth, associate professor of psychology at the University of Pennsylvania, did in a recent article she coauthored with Lauren Eskreis-Winkler for Observer magazine:

"The only thing that I see that is distinctly different about me is I’m not afraid to die on a treadmill. I will not be outworked, period. You might have more talent than me, you might be smarter than me, you might be sexier than me, you might be all of those things--you got it on me in nine categories. But if we get on the treadmill together, there’s two things: You’re getting off first, or I’m going to die. It’s really that simple. . . ."

- Oscar-nominated actor and Grammy award-winning musician Will Smith

Why is this quote pertinent to Duckworth’s work? Mainly because it’s a testimonial about grit, which she defines, on her faculty webpage, as "perseverance and sustained interest in long-term goals."

Duckworth’s research reveals that grit is an important determinant of success in almost any venture. To which you might reply, "Duh!" But before you dismiss Duckworth of espousing the obvious, you should consider the results of her research. Her "grit scale"--a brief quiz designed to measure stick-to-itiveness--has proved "remarkably predictive of success," she tells the New York Times.

Specifically, more than 1,200 freshman cadets took the grit test upon entering West Point and embarked on a grueling summer training course. "The military," notes the Times, "has developed its own complex evaluation, called the Whole Candidate Score, to judge incoming cadets and predict which of them will survive the demands of West Point; it includes academic grades, a gauge of physical fitness and a Leadership Potential Score. But at the end of Beast Barracks, the more accurate predictor of which cadets persisted and which ones dropped out turned out to be Duckworth’s 12-item grit questionnaire."

The test is, essentially, a self-assessment: It asks the cadets - or whoever is taking it - to grade their own ability to tough it out. Of course, this begs the question: Wouldn’t a group of cadets be tempted to lie about their own grittiness to impress anyone who’d judge the results? Not really, says Eskreis-Winkler.

"Even among participants at West Point, everyone in grit studies is informed that the information they share with us (the researchers) will not be shown to anyone at West Point," she says in an e-mail. "The only ‘faking’ incentive that exists is if the participant wants the random Penn researcher who sees his/her answer to think he/she is 'gritty.' No higher-ups at West Point are given information that links a specific participant’s name with his/her specific responses to the Grit Scale. This to a large degree mitigates the tendency to lie on the self-report scale."

If you’re still skeptical, we invite you to take the questionnaire yourself. It takes only three minutes. Afterward, if you’re still shaking your head at how common sense these findings are (after all, we’re talking about the simple notion of not giving up), we ask you to consider another simple notion: That not giving up is easier said than done.

Or, as Duckworth writes, "It may be obvious that effort and stamina are required to accomplish anything worthwhile in life. But how easy is it to forget this fact in moments when we feel tortoise-like relative to our seemingly hare-like peers? Who among us presses on even as we are passed by those stronger, faster, and/or smarter? Who among us stays the course, running the race we committed to rather than choosing a different, new pursuit, after stumbling and losing ground? Who lives life as if it were a marathon, not a sprint?"

This article originally appeared at The Build Network.