In the winter, Siphiwe Baleka gets some strange looks as he bikes to work over the icy, snow-laden streets of Springfield, Missouri. He fishtails around corners and does his best to avoid cars—twice he’s been hit, and both times he’s walked away. At the headquarters of Prime Inc., a long-haul trucking operation with thousands of big rigs across the country, Baleka is an oddity rolling into work on his human-powered machine.

“People always say I’m a little crazy,” he told me, laughing.

When he arrives at work each morning, he sits down at his computer to analyze the data that’s come to him via Prime’s truckers. But the numbers that blip across his screen have nothing to do with shipping inventory, engine repairs, or oil prices—Baleka’s data points deal with nutritional intake, sleep cycles, heart rate, and physical-activity rates.

When he heads down the hallway to a meeting room with members of Prime’s fleet, the 43-year-old Ironman triathlete and U.S. Master’s Swimming National Champion transforms into a motivational speaker, health counselor, and fitness instructor.

At Prime Inc. and companies like it, there’s a dire need for Baleka’s type of expertise: According to the Centers for Disease Control and Prevention, long-haul trucking, with its 3.5 million drivers, takes the top spot for the occupation with the highest obesity prevalence. Because of this, along with other factors like traffic accidents, truckers as a group have a lower average life expectancy than the general population—one study put it at just 55.7 years for owner-operator truck drivers in the U.S., and around 63 years of age for union drivers. (The average for the U.S. overall is 78.7 years.)

The long, sedentary, and often irregular hours that truckers spend behind the wheel can lead to sleep deprivation—and accumulated over a long period of time, sleep debt can disrupt the endocrine system, which regulates everything from metabolism to mood. This, in turn, can contribute to an increased risk of conditions like diabetes, obesity, and hypertension. Pressure to stay on schedule, isolation from family and friends, and scarce opportunities for healthy food can also lead to poor health and fitness.

Baleka, once a trucker himself, saw a challenge in the growing obesity epidemic: to take trucking, the unhealthiest profession in the United States, and turn it into a model for workplace wellness.

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Born Anthony “Tony” Blake in the suburbs of Chicago, Baleka was once one of the country’s top swimmers, becoming the first African American to be named All-Ivy when he competed for Yale in the 1990s. After failing to qualify for the Olympic trials for the 1992 Games, a goal he missed by just eight-tenths of a second, depression set in and he eventually dropped out of Yale a few months before graduation.

Over the next 15 years, he bounced all over the U.S. and Europe before heading to South Africa to explore his ancestral roots. While he was there, he adopted the name given to him by the locals: “Siphiwe,” which means “gift of the creator” in Zulu and Xhosa, and the last name “Baleka,” a play on “Blake” that means “fast” and “he that escaped.” Proud to have a name that reflected his heritage, he legally changed it when he returned to the U.S. for good in 2008, finally ready to settle after a decade and a half of traveling.

Back home, Baleka re-enrolled at Yale and finished the final credits to earn his diploma—but, he told me, “I didn’t have, shall we say, a viable work resume.” So when a friend suggested that his nomadic tendencies were perfectly suited for long-haul trucking, he jumped at the idea.

Baleka applied for a job with Prime Inc. and was soon spending seven-day workweeks hauling everything from flank steaks to pharmaceuticals around the country. He loved being on the road, but it didn’t take long for him to notice that he was packing on fresh pounds.

“I gained 10.7 percent of my body [weight] in the first two months, and I had never been overweight before,” he told me. “I was well on my way to becoming a statistic of being an obese truck driver.”

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As of 2012, around 92 percent of employers in the U.S. with 200 or more employees offered wellness programs, and a study from the Harvard Business Review found that they were well worth the effort, decreasing healthcare costs, reducing absenteeism at work, and boosting job satisfaction among those who participate. But still, only around 20 percent of employees with access to these programs ever take advantage of them. Even fewer stick with them for extended periods of time—one 2012 study found that around half of people who start a weight-loss program drop out within six months.

Two months into his job with Prime, Baleka took his own first steps into corporate wellness with a haphazard regimen of sit-ups, push-ups, and a fair amount of frustration that he wasn’t seeing results. After a few more months, he took his quest to the next level, trying Zumba, P-90X, and Tae Bo. He stocked his truck with resistance bands, kettle bells, dumbbells, and a weighted vest. He experimented with Weight Watchers and the paleo diet.

“As I was trying these different fitness programs, I’d have to park my truck on a relatively flat area with enough room outside the truck, set up my portable DVD player, and make sure the sun didn’t hit it and create a glare. Then I had to connect it to an external speaker, then change clothes, workout, and afterwards break everything down,” he told me. “By the time I was done with that 60-minute workout, damn near two hours had passed.”

Because truckers’ jobs can depend on their ability to deliver goods in a timely fashion, this routine wasn’t sustainable. What’s more, many of the diets Baleka tried were hard to achieve out on the open roads dotted with gas-station grub and fast-food fare. He knew if he was going to create a program that worked, it had to fit a road warrior’s lifestyle.

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In 2011, after three years as his own guinea pig, Baleka, who would later obtain his personal-trainer certification in early 2014, went to his boss to pitch what would become Prime’s Driver Health and Fitness (DHF) program. With Prime’s blessing, he promptly turned in his truck and organized a 13-week nutrition and fitness plan for truckers in the company’s fleet, built to overcome the hurdles of life on the road.

Like many drivers, 54-year-old Jeff Schottmuller approached Baleka out of fear for his own health. “I noticed my ankles were swelling and it was more difficult to walk, and I knew my blood pressure was high because of my weight,” said Schottmuller, who weighed 264 pounds at the time. “One day I looked in the bathroom mirror and thought, ‘You really let this go. If you don’t do something, you’re going to die.’”

To enroll in the program, interested drivers like Schottmuller must first meet with Baleka to discuss their goals and demonstrate that they’re ready to make big lifestyle changes. Drivers also attend a day-long orientation—which requires them to take a day away from the road—to prove their commitment, and pay an enrollment fee of $300, which they get back when they complete the program.

Using fitness-tracking armbands and apps, drivers log their meals and track their physical activity levels and receive nutritional and fitness profiles each week. The information is then transmitted back to Baleka, who analyzes their food, exercise, and sleep data to help them develop plans tailored to their individual fitness goals. Drivers also use the Skimble Workout Trainer app, which allows Baleka to assign workouts that instruct the drivers in real time on what exercises to do and for how long.

Over the past four years, he says, many of the drivers have told him that they’ve internalized the lessons they learned over the 13 weeks, and that they’ve continued to adhere to a healthier lifestyle long after they graduate from the program.

“Too much of health and fitness advice is overwhelming, which is why so many people fail,” Baleka told me. “Instead of changing everything randomly, it’s important to change a few things strategically.”

Baleka’s words echo the common wisdom among health researchers about how to keep people committed to their exercise plans. “You have to get creative, work with what’s available to you, and tailor an exercise program to your lifestyle,” said Beth Lewis, a professor in the School of Kinesiology at the University of Minnesota. “It’s important to start with small, attainable goals.”

A core principle of Baleka’s DHF program is its use of Metabolic Equivalent of Task (MET) numbers, which calculate the energy cost of physical activity as it relates to metabolism. From the exercise data and food logs submitted by the first group of 18 drivers, Baleka discovered that often, they weren’t actually overeating—it wasn’t as simple as counting calories consumed versus calories burned. He hypothesized that the largely sedentary life of a trucker meant few, if any, spikes in drivers’ MET levels, causing their metabolisms to slow.

“During the first three to four weeks of any exercise program, people have no idea how inactive they are and what counts as high intensity, versus moderate or low,” explained Sean Mullen, a professor in the department of kinesiology and community health at University of Illinois. “MET levels are a metric like anything else in that they help educate you on how intense your physical activity is, and having that knowledge allows people to plan activities more effectively to reach their goals.”

Once Baleka crunched the numbers from the program’s first group, he says, he noticed that the drivers who lost the most weight all had three things in common: They reduced their carbohydrate consumption by 10 percent, increased protein by 5 percent, and got at least four minutes of vigorous activity each day. He used this information to further hone his fitness plan, which now encourages drivers to get at least 15 minutes of daily exercise, much of it at a higher intensity to increase MET levels, thereby boosting metabolism.

“All I tell drivers is every day, you need to get out of the truck for 15 minutes and do any movements you can do with as much intensity as you can,” he told me. To make the most of those 15-minute workouts, drivers in his program do compound exercises like squats and arm curls right outside their trucks. They walk and jog laps around Walmart parking lots. When the weather is bad, they sneak in quick strength bouts in truck-stop shower stalls. No high-tech exercise equipment or weights are necessary, Baleka tells them: Just get out of the truck and move.

“I started with three five-minute walks around my parked truck each day,” Schottmuller said. “As I started to feel better, I would walk for three minutes and jog the last two and then I started adding in jumping jacks.”

Baleka’s program also has a nutritional element, built around realistic solutions for truckers confined to stops along America’s highways. “A lot of drivers like to eat a foot-long sub at Subway, but they don’t understand that it has 50-85 grams of carbohydrates just from the bread, and they don’t need all that energy just sitting in the truck where it turns to fat,” he said. “Instead, I tell them to get a six-inch sub with double meat so they take in half the carbs.”

“The reason why Siphiwe’s program works is the simplicity of it,” Schottmuller told me. He lost 33 pounds during the 13 weeks and is now down to 226 pounds with a goal of 185. “It has changed my life entirely. I’m healthier, fitter, happier, and proud of myself.”

Lewis emphasized the importance of harnessing these positive feelings as motivation for the long haul. “It’s all about teaching skills and strategies to people so when they face barriers or have relapses, they know how to get back on track,” she said. “Focusing on how they feel and their mood after exercise is one of the best natural [reinforcements] to stick with a program.”

Among the graduates of DHF, Schottmuller isn’t alone in his success. On average, drivers lose 1.6 pounds per week during the 13 weeks for a total of roughly 20 pounds, usually around 7 percent of their body weight. Thus far, around 400 of Prime’s 6,723 drivers have already completed the program.

It seems Baleka’s on to something. Everyday Health, a health and wellness website, named Prime Inc. the healthiest company of the year in 2014 thanks to DHF. And the lessons of his program, Baleka says, can be applied to almost any industry looking to create its own employee-wellness plan—or any individual looking for a creative way to get healthy. “If I can take these men and women who don’t have access to kitchens or gyms, and have changing schedules and more restrictions than the average person, [fitness programs] can work for anyone,” he told me. “I’m hoping to hold them up as a shining example of what can be done.”