Before life threw more adversity at him than one person ought to bear, Kieran Behan told his mother that he would be an Olympic gymnast someday.

He was just a boy, maybe 6 years old, when he fell in love with gymnastics, drawn to the thrill of it while watching the Summer Games, enamored by the possibility that he too could defy gravity and flip through the air as if he could fly.

But that was before a series of injuries, two so severe that doctors told him he would never walk again: a botched leg operation that caused nerve damage and a brain injury that kept him from doing even the simplest things, like sitting or eating.

Yet Behan, a 5-foot-4-inch plucky phoenix, pushed on.

“Doctors told me, stop thinking about your crazy dreams because you’ll never walk again and you must accept that it’s over for you,” Behan said. “But I just kept saying: ‘No, no, no — this is not the rest of my life. This is not how it’s going to play out.’ And look at me now, an Olympian. They said it was impossible, but I did it.”

Behan, 23, barely clinched an Olympic berth in January, qualifying second to last at the Olympic test event to become the first Irish gymnast to make it to the Games by his own talent, not by wild card. He benefited from a new Olympic rule that limits each team to five gymnasts instead of six, to make more spots available to individuals whose country does not field a full team.

Many of the powerhouse squads, including the United States’, criticized the rule change, saying it watered down the competition and forced some teams to leave a world-class gymnast at home. But the rule has an upside: it allows athletes like Behan to compete on the sport’s highest stage.

“Kieran has gone through so much,” his mother, Bernie Behan, said through tears. “He deserves this.”

Kieran Behan started gymnastics when he was 8, showing a talent for the tumbling. But soon came the first of many obstacles: when he was 10, he found a lump the size of a golf ball on his left leg.

During surgery to remove what turned out to be a benign tumor, doctors kept a tourniquet on him too tight for too long, causing nerve damage that left Behan with limited feeling in his left foot. It also caused such pain that even a slight brush against his leg would cause him to scream. He could not walk, heading to school at one point to the taunts of other youngsters who already had it out for him.

“They’d say, ‘Oh, look at the cripple,’ and that was so hard for me because, already, I was doing gymnastics and I was short, and I was doing a girls’ sport,” he said. “So a lot of times, I would sit at the kitchen window and watch all the kids running around the park and playing football, and I’d get pretty emotional. All I wanted to do was be an ordinary kid again.”

Doctors warned him that the damaged nerves might never regenerate. A psychiatrist told him to prepare him for life in a wheelchair. They were wrong.

Although it took 15 months, Behan did become an ordinary kid again. And he went back to gymnastics.

But about eight months after he returned from his leg injury, disaster hit again. In what he calls a freakish accident, he smacked the back of his head on the metal horizontal bar during a routine and tumbled to the ground in a lump.