It’s just another day at the office for Russ Gerdin, which, even these days, means it’s a pretty good day. Gerdin’s a big guy, and at 67 years of age, he looks all right for somebody who boxed with liver cancer for a couple of years, beat it back, and then learned not too long ago that it had spread to his lungs. So he’s fighting again. So far, he hasn’t let either cancer or the most severe economic downturn in 80 years keep him from running Heartland Express Inc., the trucking company he founded, took public, and still manages with an iron will and a scrupulous attention to detail that both intimidates and awes those who work for him.

Gerdin (pronounced jur-deen) is one of those unassuming Midwesterners who has quietly become a billionaire by sweating every detail in an unglamorous but indispensable business. Heartland has no debt, a nearly new fleet of 3,000 trucks, an enviable list of shipping clients, and profit margins triple those of some of its bigger competitors. Though net income was down 8 percent in 2008, the company continues to widen its lead over others in the trucking industry as scores of competitors go bankrupt.

So Gerdin has been preparing for the eventual economic rebound: He’ll buy 1,000 new trucks this year, and he recently refurbished a Texas terminal to support the company’s expansion. He’s scrambling to load up on experienced drivers who have been idled by the downturn, so that the company will be able to grow when the economy slips back into gear.

Gerdin doesn’t have a secret; he has a method. He is a grinder who pushes his employees to do dozens of little things just a tiny bit better than the competition does them. It sounds like a mundane strategy with limited application in the modern business world, but it isn’t—especially now. Sure, innovative products (iPhones) and cool new services (YouTube) get a lot of attention. But eventually, most businesses end up delivering an everyday commodity (just ask Michael Dell), and then you need someone like Gerdin who can “gut it out” rather than give up. “I’ve never had an innovative idea in my life,” Gerdin tells me during a series of interviews at Heartland’s headquarters in North Liberty, Iowa, conveniently located near the intersection of two interstates, 380 and 80.

Gerdin’s obsessive ways have built Heartland into what might be called a recession buster. Few, if any, companies are recession-proof, but in many industries, there are dominant, lean-and-mean organizations that manage to emerge from each economic downturn even farther ahead of the pack. These firms tend to be financially conservative, operating with little debt and low costs, and are tightly coiled and ready to spring into action when a downturn ends. While the more loosely run competitors are stuck fighting for survival—holding off creditors and shedding employees—the recession busters are busy trying to steal market share.

Gerdin is old-school. His office has no computer, and he doesn’t use email. He runs the company using reports, handed to him weekly, printed on old-fashioned continuous-feed computer paper, with columns of numbers showing how each truck, each customer, and each load, dispatched from one of 10 terminals across the country, is performing. When he sees something appalling, he lumbers over to the company’s sales desk, or to its dispatchers, and chews someone out. He recently delivered a tirade when he discovered that on repeated trips across Nebraska, trucks failed to detour to a customer in the small town of Crete and had been needlessly running freightless—meaning unpaid—for 121 miles.

On the day I visited, two big truck­makers, Freightliner and International, were bidding to supply Heartland’s next round of tractor trailers. “I play them both to the last dollar. It’s really dirty pool,” Gerdin says one morning. Mike Gerdin, Russ’ 39-year-old son and designated successor, walks in with a salesman from International in tow. There is a question on the trade-in value Heartland has been promised on its current rigs. Russ doesn’t like the paperwork he’s shown. “No, that’s not right,” he says, lifting an eyebrow like it’s a rifle.

He plows through a stack of papers. “See here,” he says, as his finger comes down forcefully on a number—the minimum he’ll take for the used trucks. The salesman winces, agrees to pass that along to his bosses, then shuffles out. (International later got the contract.) “I’ll do truck deals till I die,” Gerdin says. “I enjoy fighting.”

Indeed, being the wealthiest guy in town didn’t stop Gerdin from battling, over the course of 10 years, to get $750,000 in property-tax rebates from the local government when Heartland opened its new headquarters in 2007. Gerdin’s Heartland shares are valued at about $550 million. Stock sales and dividends have brought him an extra $200 million or so over the years. Shrewd real estate deals appear to put his net worth at about $1 billion, though Gerdin, who’s good at math, insists he’s currently shy of that figure.

When approached in 1986 about taking Heartland public, Gerdin says he “did not know what IPO meant.” But he did an initial public offering anyway and pocketed $13 million. “That set me up,” he says.

Since then, he has kept his Heartland salary unchanged at $300,000 a year—no bonuses, no options. To get to where he is today, he swore off old trucks and debt, and grew steadily but never spectacularly. Swift Transportation Co. and Schneider National Inc. are much bigger truck lines. J.B. Hunt Transport Services Inc. is more innovative, operating an intermodal truck-and-rail service. But of these companies, Heartland has been the most consistently profitable.

With Gerdin’s precarious health, though, there is no telling how far into an economic recovery he’ll be able to expand his company. When I visit, he tells me that he’s spent 200 of the past 300 days getting treatments or checkups. But, he adds, looking remarkably hale in his corner office, surrounded by hunting trophies, “If I’m here, I’m having a hell of a good day.”