People around the world know Dr. Kenneth H. Cooper as the father of aerobics.

But there’s another side to him: Ken Cooper, businessman.

Yes, he’s still a physician first. But being a good businessman has been his great enabler.

Today, the Cooper Aerobics Center is a 30-acre urban oasis with a nonprofit research center, medical clinic, fitness center with a restaurant, fancy spa, luxury hotel and conference center, swimming pool, tennis courts and walking trails, situated on some of the priciest real estate in Dallas.

The company also sells vitamins and supplements and offers corporate wellness programs.

All told, the family-owned company generates annual revenue of under $100 million and is profitable, says his son Tyler Cooper, the company’s CEO.

Dr. Kenneth Cooper and his Aston Martin at the Cooper Aerobic Center in Dallas (Louis DeLuca / Staff Photographer)

Once Ken Cooper was labeled a charlatan. Now, at 86, he’s considered an international treasure.

Next year marks the half-century of his best-seller, Aerobics, in which Cooper told us to get off our duffs, quit our unhealthy ways, and set in motion a national guilt trip.

To mark the 50th anniversary, Cooper is working on both an updated version of his seminal book and his memoirs.

Fitness epiphany

That has him waxing nostalgic.

The course of Cooper’s life was changed by a fateful waterskiing incident at Lake Texoma in 1960, when he was an out-of-shape, overweight 29-year-old Army medical doctor.

He’d gained nearly 40 pounds over the course of med school, his internship and early marriage and hadn’t been on water skis in eight years.

“I’d gone to pot like 80 percent of my medical school colleagues,” Cooper says.

1 / 3People workout on the machines at Cooper Aerobics Center in Dallas on May 18, 2017. (Nathan Hunsinger/The Dallas Morning News) 2 / 3People workout at Cooper Aerobics Center in Dallas on May 18, 2017. (Nathan Hunsinger/The Dallas Morning News)(Nathan Hunsinger / Staff Photographer) 3 / 3Dennis Greaney works out on the TrueStretch machine at Cooper Aerobics Center in Dallas on May 18, 2017. (Nathan Hunsinger/The Dallas Morning News)(Nathan Hunsinger / Staff Photographer)

Once behind the boat, Cooper got nauseous, his heart was racing and he thought he was having a heart attack.

It turned out to be temporary cardiac arrhythmia. But it was a permanent wake-up call.

He lost the weight in six months and ran his first marathon.

Today he’s 5-11 (having shrunk a couple of inches) and weighs 168 pounds — exactly what he weighed in high school when he was running track and playing basketball.

“I was pre-diabetic. I was hypertensive. All that disappeared after I lost that weight. I’ve kept that weight for 56 years now.

“That was divine intervention, I’m sure it was. Otherwise I was right on the same pathway as my other medical colleagues and I’d be dead already. I’m sure of it.”

In 1970, flush with $25,000 in savings and his 1968 paperback best-seller, the 39-year-old colonel and doctor left the Air Force in San Antonio, where he was responsible for the astronaut fitness program, and moved to Dallas to practice preventive medicine.

Most folks thought Cooper was loopy.

“People said, ‘There’s no way you can make a living trying to take care of healthy people. People want physicians when they’re sick and not when they’re well,’ ” Cooper says, sitting in his homey, memorabilia-filled office at the Aerobics Center on Preston Road.

“First couple of years, I thought they were right.”

He set up the Aerobics Center in a two-room office in Preston Center with two employees: another doctor and a secretary.

On the wall was an artist’s rendering proclaiming to be “Future Office of the Aerobics Center.”

A businessman, who flew from Caracas, Venezuela, after reading Aerobics, was sorely disappointed with what he found. He told Cooper to let him know when the rendering became reality.

From dream to nightmare

Cooper’s dream began to manifest in late 1971, when he moved to the Preston Road location after buying an old mansion on 8 acres and equipment using $1.2 million borrowed from Tyler Corp. Its chairman, the late Joe McKinney, was an early disciple.

The center prospered throughout Dallas’ go-go years. But things came to a screeching halt with Texas’ real estate and financial debacle. In 1988, he almost lost it all.

Ken Cooper at the Cooper Aerobics Center in 1980. (Cooper Aerobics Center)

Cooper had borrowed $15 million to invest in expansion and still owed $9.6 million when the bank that had loaned him the money failed and was taken over by NCNB of Charlotte, N.C.

NCNB, which quickly earned the nickname of No Cash for No Body in these parts, said the property was only worth $5.6 million and called the loan, even though Cooper had never missed a payment.

Cooper fought the bank for the next three years, had bankruptcy documents drawn up and spent $600,000 in legal fees.

“I was under stress like you wouldn’t believe,” Cooper says, the bitterness still apparent. “I got four foreclosure notices that last year [1991], always delivered by a messenger on a Friday afternoon at 5:30, threatening to lock the gates on Monday. I panicked the first time, didn’t sleep for a weekend. The second, third and fourth time, it didn’t bother me.”

He was finally able to renegotiate his debt.

Fifteen years later, in October 2004, Cooper paid off the loan and burned the mortgage, setting fire to the documents in a trash can.

“I don’t think we saved the ashes,” he says.

There’s no chance of taking on more debt than the company can handle, he says. “We’re solid now.”

Cooper attributes the company’s success to four things: divine intervention, an extraordinary staff that includes 24 physicians, proving to companies that wellness programs increase profits and providing service that keeps patients coming back.

“I’ve tried to impress upon our physicians that our patients don’t have to come back. They pay big dollars to come here. We don’t take insurance,” he says. “Yet we have a 74 percent return rate. Fifty-four percent are corporate-sponsored. Our patients come back because they are equally concerned about how much we care as they are about how much we know.

“That is the secret to our success as an organization.”

In 2014, Cooper became chairman and turned over the CEO reins to his son, who was born eight days after Ken saw his first patient at the center.

Several times during our multiple interviews, Cooper said the company’s future is in Tyler’s hands, particularly when it comes to the grand plan of establishing the Cooper brand internationally.

Does this signal that the patriarch is heading toward the corporate finish line?

The question — posed separately to both — draws equally incredulous responses.

“I’m confident that my dad will be thinking of something new and working on improving health around the world until the day he dies,” Tyler Cooper says. “There’s no last hurrah in my dad’s mindset.”

“What is retirement?” says Ken Cooper. “I like what [the late inspirational speaker] Zig Ziglar once said: ‘You don’t retire, you re-fire.’ I get bored easily.”

Once a week, Ken Cooper indulges in his one guilty pleasure: Driving his beloved 2006 Aston Martin DB9 convertible that he bought new. The steel-gray high-powered sports car only has 18,000 miles on it.

“That’s my James Bond car,” he says. “It’s a beautiful, wonderful car, no problem at all. I keep it in perfect condition. The only luxuries I have in my life are my wife and my Aston Martin.”

Kenneth H. Cooper

Title: Chairman Cooper Aerobics

Age: 86

Born: Oklahoma City

Education: Bachelor of science and doctor of medicine, University of Oklahoma; master of public health, Harvard University School of Public Health

Personal: Married to Millie for 57 years. They have a daughter, Berkley, 51, and son, Tyler, 46 and five grandchildren

Tyler Cooper

Title: President and CEO, Cooper Aerobics Enterprises Inc.

Age: 46

Education: Bachelor of business administration, Baylor University; doctor of medicine, University of Texas Medical School at San Antonio; and master of public health in health care management, Harvard University

Personal: Married to Angie for 15 years. They have sons, 11 and 7, and a daughter, 9

Cooper Aerobics Center

Address: 12200 Preston Road

Founded: 1970 in Preston Center

Annual revenue: Under $100 million

Ownership: Ken Cooper and his family with small stakes owned by physicians

Employees: 24 physicians, 535 full-time and part-time staff

Includes: Cooper Clinic, Fitness Center, Spa, Hotel, Cooper Complete vitamins and supplements, Cooper Wellness Strategies and a not-for-profit research arm, The Cooper Institute.

SOURCES: Cooper Aerobics Center; Ken Cooper; Tyler Cooper