Angela Lee Duckworth, a former consultant at McKinsey, knows all about pushing past limits. 

At the age of 27, Duckworth left her high-flying post in management consulting to teach math in New York City's public schools. As a teacher she realized some of her strongest performers didn't have "stratospheric IQ scores," but would fare better on their tests than their smarter peers. 

What was the missing link between their limited abilities and their performance? Duckworth knew immediately it had to be grit. All the students could learn the material if they worked long and hard enough at it. Innate intelligence wasn't a factor--what mattered was doing the work.  

"Grit is passion and perseverance for very long-term goals," Duckworth said in a recent TED talk. "Grit is having stamina. Grit is sticking with your future, day in, day out, not just for the week, not just for the month, but for years, and working really hard to make that future a reality. Grit is living life like it's a marathon, not a sprint."

Perhaps the most remarkable thing about grit, she continued, was how little scientists understand it. So far, the best idea she's heard is growth mindset, the belief that the ability to learn is not fixed and can change with your effort.

"We need to take our best ideas, our strongest intuition, and we need to test them," Duckworth said. "We need to measure whether we've been successful, and we have to be willing to fail, to be wrong, to start over again with lessons learned."

How have you applied grit at your business?