researcher asked afterward how they felt, one of the radish eaters said he was “sick of this dumb experiment.”
“By making people use a little bit of their willpower to ignore cookies, we had put them into a state where they were willing to quit much faster,” Muraven told me. “There’s been more than two hundred studies on this idea since then, and they’ve all found the same thing. Willpower isn’t just a skill. It’s a muscle, like the muscles in your arms or legs, and it gets tired as it works harder, so there’s less power left over for other things.”
Researchers have built on this finding to explain all sorts of phenomena. Some have suggested it helps clarify why otherwise successful people succumb to extramarital affairs (which are most likely to start late at night after a long day of using willpower at work) or why good physicians make dumb mistakes (which most often occur after a doctor has finished a long, complicated task that requires intense focus). [132] “If you want to do something that requires willpower-like going for a run after work- you have to conserve your willpower muscle during the day,” Muraven told me. “If you use it up too early on tedious tasks like writing emails or filling out complicated and boring expense forms, all the strength will be gone by the time you get home.” [133]
But how far does this analogy extend? Will exercising willpower muscles make them stronger the same way using dumbbells strengthen biceps?
In 2006, two Australian researchers-Megan Oaten and Ken Cheng-tried to answer that question by creating a willpower workout. They enrolled two dozen people between the ages of eighteen and fifty in a physical exercise program and, over two months, put them through an increasing number of weight lifting, resistance training, and aerobic routines. [134] Week after week, people forced themselves to exercise more frequently, using more and more willpower each time they hit the gym.
After two months, the researchers scrutinized the rest of the participants’ lives to see if increased willpower at the gym resulted in greater willpower at home. Before the experiment began, most of the subjects were self- professed couch potatoes. Now, of course, they were in better physical shape. But they were also healthier in other parts of their lives, as well. The more time they spent at the gym, the fewer cigarettes they smoked and the less alcohol, caffeine, and junk food they consumed. They were spending more hours on homework and fewer watching TV. They were less depressed.
Maybe, Oaten and Cheng wondered, those results had nothing to do with willpower. What if exercise just makes people happier and less hungry for fast food?
So they designed another experiment. [135] This time, they signed up twenty-nine people for a four-month money management program. They set savings goals and asked participants to deny themselves luxuries, such as meals at restaurants or movies. Participants were asked to keep detailed logs of everything they bought, which was annoying at first, but eventually people worked up the self- discipline to jot down every purchase.
People’s finances improved as they progressed through the program. More surprising, they also smoked fewer cigarettes and drank less alcohol and caffeine-on average, two fewer cups of coffee, two fewer beers, and, among smokers, fifteen fewer cigarettes each day. [136] They ate less junk food and were more productive at work and school. It was like the exercise study: As people strengthened their willpower muscles in one part of their lives-in the gym, or a money management program-that strength spilled over into what they ate or how hard they worked. Once willpower became stronger, it touched everything.
Oaten and Cheng did one more experiment. They enrolled forty-five students in an academic improvement program that focused on creating study habits. [137] Predictably, participants’ learning skills improved. And the students also smoked less, drank less, watched less television, exercised more, and ate healthier, even though all those things were never mentioned in the academic program. Again, as their willpower muscles strengthened, good habits seemed to spill over into other parts of their lives.
“When you learn to force yourself to go to the gym or start your homework or eat a salad instead of a hamburger, part of what’s happening is that you’re changing how you think,” said Todd Heatherton, a researcher at Dartmouth who has worked on willpower studies. [138] “People get better at regulating their impulses. They learn how to distract themselves from temptations. And once you’ve gotten into that willpower groove, your brain is practiced at helping you focus on a goal.”
There are now hundreds of researchers, at nearly every major university, studying willpower. Public and charter schools in Philadelphia, Seattle, New York, and elsewhere have started incorporating willpower- strengthening lessons into curriculums. At KIPP, or the “Knowledge Is Power Program”-a collection of charter schools serving low-income students across the nation-teaching self-control is part of the schools’ philosophy. (A KIPP school in Philadelphia gave students shirts proclaiming “Don’t Eat the Marshmallow.”) Many of these schools have dramatically raised students’ test scores. [139]
“That’s why signing kids up for piano lessons or sports is so important. It has nothing to do with creating a good musician or a five-year-old soccer star,” said Heatherton. “When you learn to force yourself to practice for an hour or run fifteen laps, you start building self-regulatory strength. A five-year-old who can follow the ball for ten minutes becomes a sixth grader who can start his homework on time.” [140]
As research on willpower has become a hot topic in scientific journals and newspaper articles, it has started to trickle into corporate America. Firms such as Starbucks-and the Gap, Walmart, restaurants, or any other business that relies on entry-level workers-all face a common problem: No matter how much their employees
“For a lot of employees, Starbucks is their first professional experience,” said Christine Deputy, who helped oversee the company’s training programs for more than a decade. “If your parents or teachers have been telling you what to do your entire life, and suddenly customers are yelling and your boss is too busy to give you guidance, it can be really overwhelming. A lot of people can’t make the transition. So we try to figure out how to give our employees the self-discipline they didn’t learn in high school.”
But when companies like Starbucks tried to apply the willpower lessons from the radish-and- cookie studies to the workplace, they encountered difficulties. They sponsored weight-loss classes and offered employees free gym memberships, hoping the benefits would spill over to how they served coffee. [141] Attendance was spotty. It was hard to sit through a class or hit the gym after a full day at work, employees complained. “If someone has trouble with self-discipline at work, they’re probably also going to have trouble attending a program designed to strengthen their self-discipline
But Starbucks was determined to solve this problem. By 2007, during the height of its expansion, the company was opening seven new stores every day and hiring as many as fifteen hundred employees each week. [142] Training them to excel at customer service-to show up on time and not get angry at patrons and serve everyone with a smile while remembering customers’ orders and, if possible, their names-was essential. People expect an expensive latte delivered with a bit of sparkle. “We’re not in the coffee business serving people,” Howard Behar, the former president of Starbucks, told me. “We’re in the people business serving coffee. Our entire business model is based on fantastic customer service. Without that, we’re toast.”
The solution, Starbucks discovered, was turning self-discipline into an organizational habit.
III.
In 1992, a British psychologist walked into two of Scotland’s busiest orthopedic hospitals and recruited five-dozen patients for an experiment she hoped would explain how to boost the willpower of people exceptionally resistant to change. [143]
The patients, on average, were sixty-eight years old. Most of them earned less than $10,000 a year and didn’t
