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

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

But theres another side to him: Ken Cooper, businessman.

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

Age: 86

Claim to fame: Got America focused on fitness with his best-seller Aerobics, published in 1968.

Start: Was as Air Force doctor responsible for the astronaut fitness program

Now: Chairman of family-owned company medical clinic and fitness operation with revenue close to $100 million.

Source: Dallas Morning News

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

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

The family-owned company generates annual revenue that will approach $100million this year and is profitable, said his son Tyler Cooper, the companys CEO.

Once Ken Cooper was labeled a charlatan. Now at 86, hes 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 and quit our unhealthy ways. He set in motion a national guilt trip.

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

The course of Coopers life was changed by a water-skiing incident at Lake Texoma in 1960, when he was an out-of-shape, overweight 29-year-old Army medical resident.

Hed gained nearly 40 pounds over the course of med school, his internship and early marriage, and hadnt been on water skis in eight years.

Id gone to pot, like 80 percent of my medical-school colleagues, Cooper said.

Once behind the boat, Cooper got nauseated, 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 hes 5 feet, 11 inches tall (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 prediabetic. I was hypertensive. All that disappeared after I lost that weight. Ive kept that weight for 56 years now.

That was divine intervention, Im sure it was. Otherwise I was right on the same pathway as my other medical colleagues and Id be dead already. Im sure of it.

In 1970, flush with $25,000 in savings and a 1968 paperback best-seller (Aerobics), 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 people thought Cooper was loopy.

People said, Theres no way you can make a living trying to take care of healthy people. People want physicians when theyre sick and not when theyre well, Cooper said. First couple of years, I thought they were right.

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

Coopers dream began to manifest in late 1971, when he borrowed money to move to an old mansion on 8 acres.

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.

Cooper had borrowed $15 million to invest in expansion and still owed $9.6 million when the bank that lent him the money failed and was taken over.

The new out-of-state bank said the property was worth only $5.6million 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 wouldnt believe, Cooper said. I got four foreclosure notices that last year of 91, always delivered by a messenger on a Friday afternoon at 5:30, threatening to lock the gates on Monday. I panicked the first time, didnt sleep for a weekend. The second, third and fourth time, it didnt bother me.

He finally was able to renegotiate his debt.

Fifteen years later, in October 2004, Cooper paid off the loan and burned the mortgage.

I dont think we saved the ashes, he said.

Cooper attributes the companys 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.

Ive tried to impress upon our physicians that our patients dont have to come back. They pay big dollars to come here. We dont take insurance, he said. 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.

Cooper said the companys future is in Tylers 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 draws equally incredulous responses from both.

Im confident that my dad will be thinking of something new and working on improving health around the world until the day he dies, said Tyler Cooper. Theres no last hurrah in my dads mindset.

More:

Aerobics pioneer still in the fitness business at 86 - The Seattle Times