"You're never going to race again."
That's what doctors told Ryan Reed after his blood work came back. The 17-year-old had been diagnosed with Type One diabetes, which can be deadly.
Reed had been racing since he was a toddler and was on the brink of breaking into NASCAR.
"At that point, you know, a doctor tells you your career is over," Reed told CNBC. "I didn't know what to do."
After wrestling with the news, the teenager realized that before giving up, he needed to try everything that he could. He researched the disease and stories of athletes with diabetes, and he found the right doctors to help him.
Just two year later, Reed made his first professional start with NASCAR at age 19. Today is a driver for Roush Fenway Racing in the NASCAR XFINITY Series.
As Reed, now 23, put it, "I was determined to find out, to make sure that I didn't leave any stone un-turned."
Refusing to give up during those difficult years of uncertainty left a mark on him.
"It really shaped the rest of my career and shaped my mindset towards my work ethic."
Reed's story supports psychological research that shows the importance of determination.
Psychologist Angela Duckworth found that Olympic athletes, actors, and other high achievers shared two common traits: grit and self-discipline.
According to Duckworth, skill is the product of talent or potential multiplied by how much effort and work you put in. People who work consistently at something are more likely to succeed.
Additionally, Stanford University research has shown that people who view ability as something that can be learned or attained are more likely to succeed after setbacks. It was Reed's belief that he could find a way that propelled him to keep fighting.
Inside the driver's car, next to his oil pressure, water temperature, and RPM gauges, is his continuous glucose monitor. Reed worked with doctors to use technology to keep his career moving ... at about 150 miles per hour.
"It fits next to all my other gauges. It becomes just part of my dash on my race car," he said.
In short, he realized, "You're going to succeed at some point if you just refuse to give up."