For most of his life, Sean Roberson watched his brother struggle with diabetes. The seizures the disease produced when his blood sugar dipped. The insulin shots he took to manage it.

“He never complained,” Roberson remembered recently. “He just accepted it as part of his life.”

But diabetes, the leading cause of kidney failure nationally, can overwork the kidneys until they wear out.

In the fall of 2008, Michael Roberson learned his kidneys were failing.

He needed a new one and Sean Roberson had one to spare. If a kidney was all his brother needed, this was a small thing to do.

“It was clear someone needed to step up, so I did,” Sean Roberson said as he sipped a cup of black coffee.

Three months later, Roberson went in to be tested.

What hadn’t been so clear in that moment to the then-26-year-old was how efforts to save Michael’s life would change his and usher in a new purpose.

Doctors told Roberson, of Lawrenceville, that he was a perfect match for his brother but, at nearly 250 pounds, he needed to lose at least 27 pounds before the transplant.

Sean Roberson hated going to the gym, and there was no way he was going to pay a trainer.

“That’s when I decided to run,” said Sean, now a 32-year-old finance process consultant with Ernst & Young.

Twice a day, he hit the pavement, running 3 to 5 miles at a time five days a week. Within a month, the pounds were melting away like ice under a hot summer sun.

“I was pumped,” Sean Roberson remembered, smiling. “I stopped eating carbs and sugar.”

Doctors assured him he was doing great, to keep it up.

By May 2009, he’d dropped all the pounds he needed and then some. He weighed in at 222.

Doctors scheduled the surgery, and early on the morning of June 17, 2009, he and Michael headed to the Jewish Hospital Transplant Center, not far from the home where the two of them had grown up in Louisville, Ky.

As they stared into the darkness, their father offered a pep talk. Be grateful, Michael, for this second chance. This transfer of organs connects you for the rest of your lives. God is good.

Sean Roberson had always wondered why God chose Michael for this journey. There had been so many days when he wished it were him. If he could take on some of the pain, he told himself, he would do so gladly.

Now, finally, he could do something.

“It always hits me when I think about it,” he said, bowing his head to catch the tears welling in his eyes.

At the hospital, the brothers were taken to two different rooms and prepped for the transfer.

“When I woke up four hours later, it was over,” Sean Roberson said.

So, too, was life as he knew it.

“Out of that experience, I began to contemplate my purpose,” he said.

By 2012, he knew a big part of that was to share Michael’s story and, more importantly, to encourage others to exercise and eat healthy.

And so he asked himself: How could he turn helping people live healthy lives into something he did every day?

RunBabyRun was his answer.

Through it, Roberson has been forming running groups, holding health fairs, posting healthy eating tips through Instagram feeds and on Facebook, and to date, has helped build one of three gardens he plans to donate to needy families.

He also has developed a line of activewear apparel that includes T-shirts, running tights and shorts that are sold online at www.runbabyrunatl.com and at running events such as the Peachtree Road Race.

Proceeds from the sale of merchandise go toward juvenile diabetes research.

Giving his brother Michael Roberson, now 34, a kidney was pretty simple, Roberson said. This new journey is a little more complex.

But he is convinced this is the path God chose for him, and he has no intention of turning back.

That is, perhaps, the real miracle in this story.