Most people have days they’ll never forget. For me, that day is April 26, 2011.

It was my first time appearing on National Public Radio. As part of the program All Things Considered, host Michele Norris interviewed me about my research that suggested increasing narcissism in pop music lyrics. Michele was curious, insightful, and put me at ease. When I left my office and walked to my car, I felt light as a feather floating across campus, free of care and worry. I had no idea that what would happen over the next 24 hours would upend everything in my life. That day would take me down a different path—one that included regularly running 100-mile footraces.

This is the story of how I use the science of self-control to run ultramarathons. I believe that self-control is our greatest human strength, and the easiest thing that we can improve upon. By mastering the three components of self-control, you too could run 100 miles—or conquer other, seemingly unreachable professional and personal goals.

But before I marinate you in data, let’s return to that Tuesday night in April.

Why run 100 miles?

I never planned on running 100-mile races. I didn’t even know people did that sort of thing. But I can trace my path from sedentary academic to ultramarathon runner back to a phone call I made to my mother on that Tuesday night in 2011. She was my biggest fan and supporter. Whenever something big happened, Mom was my first call. This night was no exception.

She told me that she was proud of me. I told her that my college roommate had heard the interview on the radio: “He said he nearly choked on his piece of salmon.” We laughed a lot. Before we hung up, Mom told me she loved me. I can’t remember if I said I loved her back. But she knew I did.

I can trace my path from sedentary academic to ultramarathon runner back to a phone call I made to my mother on a Tuesday night in 2011.

That was the last time I spoke with my mom. The next day, she tripped in her driveway, hit her head, and her brain started to bleed. The doctors couldn’t stop the bleeding. She died five days later. I couldn’t believe it. My world was shaken. For months, I couldn’t sleep.

I started exercising to dull the pain of bereavement. And to support my wife, Alice, I joined her in enrolling in a weight-loss program. At my intake session, I stepped on the scale. The nurse gently told me that my body mass index (BMI) put me in the obese range.

“Obese? I’m not obese,” I said. “I’m tall.”

She pointed to a chart on the wall. “Let’s see. You’re 6 feet 2 inches (1.88 meters). That is tall,” she said. Then she dragged her finger to the part of the chart that matched my weight. She said, “You’re tall and obese.”

Little by little, I improved my diet and became more active. I lost weight. Then Alice told me about two books she had read, Ultramarathon Man by Dean Karnazes and Eat and Run by Scott Jurek. In each book, the authors described running 100 miles without stopping. They even talked about running a race called the Badwater ultramarathon, a 135-mile, nonstop, invitation-only race across Death Valley in July.

Instantly, I knew that this was something I wanted to do. I had never even run a regular marathon. But that didn’t matter. Karnazes and Jurek described ultramarathons as life-altering, almost spiritual experiences. I’ve always been driven and prone to take on wild, seemingly unattainable goals. People who ran ultramarathons seemed like my kind of tribe.

The spark was lit. And as a psychologist, I had already studied the key ingredient I would need to accomplish my new, crazy running goals: self-control. Now I just needed to figure out how to apply that knowledge to my personal life.

The gift of willpower

People with a lot of self-control have the motivation and ability to override their unwanted impulses and desires. You can tell a lot about people’s self-control by how they act around marshmallows. Just ask Walter Mischel, who conducted one of psychology’s classic studies using nothing more than a bag of marshmallows and some adorable kids enrolled at Stanford’s Bing Nursery School. Mischel gave each child a simple task: They could have one marshmallow right away, or they could wait patiently to earn a second marshmallow. Unbeknownst to the kids, the true purpose of the study was to examine their persistence in the face of temptation. They had to delay immediate gratification for a delayed reward.

What happened next shocked Mischel and the rest of the academic world. Kids who delayed gratification in nursery school went on to enjoy happier, healthier, and more successful adult lives. Kids with willpower were more prone to later success, because they built the habit of crowding out temptation to remain laser-focused on their goals.

Self-control was over twice as important as intelligence in predicting children’s academic success.

Indeed, self-control seems to be a key factor in determining academic achievement. In a clever 2005 study, psychologists Angela Duckworth and Martin Seligman measured 140 eight-graders’ self-control and intelligence. Then Duckworth and Seligman waited patiently until the end of the school year, when they recorded the students’ end-of-year grade point averages. The results? Self-control was over twice as important as intelligence in predicting children’s academic success.

In their best-selling book Willpower: Rediscovering the Greatest Human Strength, psychologist Roy Baumeister and science journalist John Tierney offer many additional examples of the benefits of self-control. They show how self-control helped musician Eric Clapton to kick his alcohol and drug addiction and comedian Drew Carey learn to flourish at his work. One particularly memorable detail: Mastering the components of self-control helped magician David Blaine complete his feats of physical endurance, including holding his breath underwater for over 17 minutes.

If Blaine could hold his breath underwater for 17 minutes, could I train my body and mind to run 100 miles? It seemed possible. And so I set about fortifying my sense of self-control, based on the following factors:

Standards are the reference points you use to determine whether a given action is appropriate or desirable—whether you should order a third drink, for example, or wake up at 5 am every day. Our standards originate from our cultural surroundings, what people teach us, and our personal beliefs.

are the reference points you use to determine whether a given action is appropriate or desirable—whether you should order a third drink, for example, or wake up at 5 am every day. Our standards originate from our cultural surroundings, what people teach us, and our personal beliefs. Monitoring is the second part of self-control. If you want to control your thoughts, feelings, and behaviors, you have to keep track of them.

is the second part of self-control. If you want to control your thoughts, feelings, and behaviors, you have to keep track of them. Strength refers to how much energy you have to control your impulses. Your strength waxes and wanes as the day goes on, usually peaking in the morning and plunging at night. You can also build up strength through practicing self-control.

Putting self-control into practice

Reading about running 100 miles is one thing. Doing it is another. I quickly learned how little I knew about the sport. To prevent injury, I hired an online running coach. My coach and I developed standards for training, methods to monitor my running, and discussed how to maintain and build my physical and mental strength.

Standards : I ran six days a week, building my mileage slowly until I was running between 60 and 85 miles per week. Although I started by running one or two miles per day, less than a year later I could run 20 miles on a Saturday and another 20 miles the following day.

: I ran six days a week, building my mileage slowly until I was running between 60 and 85 miles per week. Although I started by running one or two miles per day, less than a year later I could run 20 miles on a Saturday and another 20 miles the following day. Monitoring : I recorded every workout online, which helped me monitor my progress over time. I recommend Strava. It’s where I log my workouts. I noticed that I was spending the same amount of time running as I had been spending watching television. It helped me realize that I had always had the time to run; I’d just been doing something else with it.

: I recorded every workout online, which helped me monitor my progress over time. I recommend Strava. It’s where I log my workouts. I noticed that I was spending the same amount of time running as I had been spending watching television. It helped me realize that I had always had the time to run; I’d just been doing something else with it. Strength: To maintain my physical strength, I experimented with sports foods and drinks that I would consume while I ran. I currently use SWORD for all of my running. It’s liquid gold. I built my mental strength by running even when I didn’t want to—when I was sore, stressed, or sleepy.

It took a year of training before I arrived at the starting line of my first 100-mile race, the Hallucination 100 miler in Hell, Michigan. (Yes, I traveled to Hell to run 100 miles.)

At the starting line, I knew I needed to incorporate the three ingredients of self-control if I had any chance at finishing. The race had a 30-hour time limit. To complete it successfully, I had to maintain at least an 18:00 minute/mile (11:11 minute/km) pace. How hard could that be?

I had to monitor how many miles I ran, along with the number of calories I consumed each hour. That also seemed easy. And I needed to draw on the physical and mental strength I had cultivated during my training to run even when I didn’t want to.

But I quickly realized that it would take every shred of my self-control to run 100 miles. By the time I had run 30, my leg muscles were burning. By the time I had run 60, I was sleep-deprived and stumbling. By the time I hit mile 83, I knew that I had no chance of finishing.

I thought I had done everything right. I’d prepared well; I ate every 20 minutes; I rehydrated consistently; and I was in good physical shape. Still, my mind was failing me. I needed a boost of strength from self-control.

When I saw Alice at mile 83, I felt like—and resembled—a ghost.

“I need help,” I said. “Can you help me?

“What do you need? I’ll do anything.”

“Will you do the last part with me?” I asked, knowing that Alice had never done more than a 5-K race.

“Of course I will,” she said.

Acts of extreme self-control are made possible by close relationships.

We covered the last 17 miles together, with her encouraging me every step of the way. When I whined, she told me to eat. When I said I needed to sit down, she told me to keep moving. When I crossed the finish line, after 26 hours and 42 minutes of running, she gave me a hug, a kiss, and told me she loved me.

There are two points to this story. First, Alice is an incredible partner. But the second, broader point is that acts of extreme self-control are made possible by close relationships. As Malcolm Gladwell astutely points out in Outliers, achieving eminence in a given field is about more than just 10,000 hours of deliberate practice. Bill Gates spent thousands of hours learning how to program computers—but he only had that opportunity because he had the good fortune of having parents who supported his education. Mozart spent most of his youth performing and composing, which was made possible by his father Leopold, who sacrificed his own goals to ensure that young Wolfgang had what he needed to succeed.

To even make it to the starting line of my first 100-mile race, I needed to have a partner who supported me. And I certainly needed Alice to finish it. Self-control and close relationships are the two components necessary for success.

The spillover effect

Since that first ultramarathon, I’ve run a slew of long races, including the Last Annual Vol State 500km (314-mile) race and the 147-mile Marathon des Sables stage race in the Sahara Desert. I’ve helped friends finish races and break world records for running across the United States. And after five years of running, I achieved my big goal: I was invited to toe the starting line at this year’s Badwater 135 ultramarathon on July 10.

Once you build self-control through a chosen activity, you do a better job exerting self-control in other situations.

But the bigger payoff of running ultramarathons has been at the office and at home. By strengthening my body and mind, I’ve been able to accomplish more at work and become a better husband and father. Succeeding at relationships and at work also requires self-control. Self-control can help you override undesirable urges, like snapping at your partner or putting off a big project. And the good news is that strengthening self-control in one area of your life can improve other components of life. It’s the gift of self-control spillover.

Once you build self-control through a chosen activity—whether it’s running, quitting smoking, getting on a budget, or finally buckling down and writing your book—you do a better job exerting self-control in other situations. Consider a simple experiment by psychologist Tom Denson and his colleagues. They conducted a study in which half of all participants practiced self-control over two weeks by using their non-dominant hand for everyday tasks (for example, cooking and carrying their books). The rest of the participants were in the control group, assigned to perform undemanding tasks.

Next the researchers insulted all the participants by giving them negative feedback on a public speech, and waited to see if they would react aggressively. It takes self-control to override aggressive impulses, whether it’s toward a colleague who rubs you the wrong way or a family member who’s criticizing the way you wash the dishes. The study found that the people who had practiced self-control with their non-dominant hands—an activity that had no bearing on the situation at hand—were better able to keep their tempers in check. The bottom line: Practice self-control in one area of your life, and you can apply it in other parts, too.

Successful entrepreneurs and businesspeople have long testified to the benefits of self-control. “Grit is every entrepreneur’s trump card,” said LinkedIn founder Reid Hoffman on his podcast Masters of Scale. In his comprehensive biography of Elon Musk, Ashlee Vance shows readers how Musk’s genius consists of setting incredibly high standards, monitoring progress closely, and working around the clock to build his physical and mental strength. The result? Companies that are deftly disrupting and redefining the automotive and space industries.

As I reflect on that Tuesday in April, 2011, I feel a mixture of sadness and gratitude. What started as a way to cope with grief became an opportunity for growth. I’m reminded of the book Option B: Facing Adversity, Building Resilience, and Finding Joy, by Facebook chief operating officer Sheryl Sandberg and psychologist Adam Grant, which focuses on life after loss. After the unexpected death of Sandberg’s husband, a friend told her, “Option A is not available. So let’s just kick the shit out of Option B.” I’m living my own Option B now. And running 100 miles helps me kick the shit out of it.