Ever since 39-year-old Bonner Paddock was a child, he has carried what he calls “the dark rider” with him every step of the way.

When Paddock was 11, he was diagnosed with cerebral palsy (CP). Since then, he has tried to ignore this companion’s presence— even as it persisted to make his muscles ache and his body to move with an abnormal gait where his toes, rather than his heel, hit the ground when he propels forward.

His attitude changed in his late 20s, when he found a way to channel his “dark rider” to raise awareness about CP— by tackling seemingly insurmountable pursuits for someone with his condition. In 2008, he climbed Mt. Kilimanjaro, the tallest freestanding mountain in the world, unassisted. Then, in 2012, he completed the Ironman World Championship, among lava fields in Kailua-Kona, Hawaii. Paddock was the first person with CP to accomplish both feats. Paddock details how he overcame these challenges, as well as his struggle to accept CP, in his new book, “One More Step.”

Ignoring the signs

From the time he could stand on two feet, Paddock always had an unusual stride, characterized by walking on the tippy-toes with bent knees. It never held him back from keeping up with his two older brothers, Mike, 47, and Matt, 42, throughout the boys’ adolescence in Arcadia, Calif. But doctors weren’t sure what the underlying cause of his gait was.

“I hated doctors,” Paddock told FoxNews.com. “You get probed. They stuck things in my head with putty— you feel like Pinhead. Remember him from the movies? They were throwing these electrical currents through your body because they wanted to see how the brain measured them. And then they’d put these probes at the bottom of your feet … and they put currents in the feet to see if the brain could tell because that’s where I was having the least coordination.”

Among the numerous doctors Paddock saw while growing up, two of them thought Paddock had syringomyelia, a condition marked by a buildup of fluid-filled cyst in the spinal cord. One doctor predicted he would be wheelchair-bound by age 15 and likely wouldn’t live past age 20. But Paddock’s mother was never convinced that’s what he really had, so he continued to undergo tests.

Eventually, Dr. Arnold Starr at University of California Irvine Health diagnosed Paddock with spastic diplegia CP, which is characterized by the brain’s inability to signal the lower body to relax.

Types of CP vary, and the condition can be concentrated to one part of the body— in Bonner’s case, from his lower back to his feet— or it can impact the whole body. According to the Mayo Clinic, people with spasticity have exaggerated reflexes and stiff muscles.  

Severe cases of CP require wheelchair assistance, but those with spastic diplegia, like Paddock, can walk without aid. Doctors determined that Paddock developed CP when his umbilical cord wrapped around his neck in the birth canal.

Growing up with CP

Following his diagnosis, Paddock went to physical therapy three to five times a week. His first crush was his physical therapist. But, even after determining what caused his unusual movement, Paddock’s family never discussed CP.

“Looking back on it, it seems absolutely crazy,” Mike McConnell, Paddock’s brother, told FoxNews.com. “At that time, it was ‘normal’ for us to just not talk about it, and I think one thing that did help him along was he was treated normal. Within the family, he would go with me and my brother Matt, and we’d play baseball, and he wanted to participate, and we never said, ‘No, Bonner, you can’t do it, you have CP,’ [but] we might’ve done it because he was our younger brother.”

Paddock wasn’t afraid to play any sport— be it tennis, basketball or soccer, which he enjoyed because they required more hand-eye coordination rather than speed. In soccer, teams stuck him in front of the net, an assignment Paddock enjoyed because no one else wanted to be the goalie, and he was good at it.

Sports were a means to win for Paddock and a way to feel accepted. But often, his approach backfired.

“I was horrible,” Paddock said. “When someone would score a goal on me, I’d kick the post, I’d kick the ground, I’d cry. I was a terrible sport, a terrible loser. I didn’t have a lot of friends not because of my CP but because of my attitude. Who wants to hang out with that kid? I wouldn’t.”

The dark rider

As Paddock entered adulthood, his secret became bigger. When people would ask him why he walked funny, he’d tell them it was an old soccer injury, or a hip or knee injury. Paddock refused to fully face his diagnosis, staying mum on the truth about his condition through business school at San Diego State University, as well as during subsequent jobs.

When he finally revealed his diagnosis, at age 29, after a year of working at Seaver Marketing Group, he only did so because he felt he wouldn’t be judged. His boss, Ron Seaver, immediately asked him if he needed help with anything, like a closer parking space.

“So I left and went back to my desk and thought, ‘Well, that was awkward, and I’m an idiot,’” Paddock said. “You build it up in your own head, and that’s what I started learning.”

During the interview process for his next job, Paddock took an even bigger leap and revealed he had CP. He got the job with the Anaheim Ducks hockey team.

At the time, the National Hockey League (NHL) was in the middle of the 2004-2005 lockout, and some of the employees with the team began donating their free time to charity work. Paddock did an Internet search and found United Cerebral Palsy of Orange County (UCP-OC), the local chapter of an organization that aims to raise awareness and funds for people diagnosed with CP.

Paddock was invited to share his story with the UCP-OC board, an experience that made him feel sick to his stomach as he had to face his CP head-on. At the time, he didn’t even know that there were various types of CP or remember the name of which kind he had.

The meeting ended up being the catalyst that forced Paddock to bring his dark rider further into the light. He befriended the man he sat next to, Steven Robert, whose son had a severe case of CP that disabled him from walking. After hearing Paddock’s story, Robert called him on the phone and told him how inspired he was by it.

“That was a lightning bolt to the heart in terms of: somebody’s openly accepting me, and I give them hope for not really doing anything except for being me or trying to be me,” Paddock said. “That just started this bizarre, great journey of really trying to knock down all the walls I’d put up for 30 years and try to build a different structure of happiness.”

To join the board of directors for UCP-OC, Paddock needed to run in a fundraiser 5K, half marathon or full marathon. He’d never run in a formal race— as a kid, he wasn’t even allowed to wear running shoes because he’d walked on his tippy-toes, he pointed out, so he could only wear flat shoes like K-Swiss.

Paddock ran a mile one day and three miles the next, and then essentially just showed up at the 13.1-mile race. He finished, but a dark cloud hung over the accomplishment: the death of Robert’s son, Jake, 4, at the hands of CP on the night of the half marathon.

The next year, in 2006, Paddock ran a full marathon in Jake’s memory and got the attention of local press in Orange County.

“That stoked the fire that maybe if I do these endeavors or physical adventures, this is going to be a great way to raise awareness and a great way to raise a ton of money for CP,” Paddock said.

Defying the odds

In the 11 months prior to his Mt. Kilimanjaro climb, Paddock had been hiking various mountains around California. He caught the attention of his neighbor, Afshin Aminian, who, simply by observing Paddock, knew he had CP. Aminian, a pediatric orthopedic surgeon at Children’s Hospital of Orange County, questioned Paddock’s choice to make the hike in Africa.

“I said, ‘Some people die when they do this,’ and he said, ‘I know what I’m doing,’” Aminian, who lives in Santa Ana, Calif., told FoxNews.com.

Aminian and Paddock had multiple conversations about Paddock’s choice to take on the challenge, as Paddock’s aversion to doctors deterred him from seeking out medical advice beyond that from his general physician. Aminian warned Paddock that because his equilibrium was off due to CP, and the terrain is unpredictable, he was at a higher risk of physically harming himself than a hiker without the condition.

Paddock pointed out that, before making the climb, he knew the high altitude he’d encounter also could be deleterious to his neurological health: Having CP meant his brain would be at risk of swelling and smashing against his skull, producing searing headaches. Despite that knowledge, Paddock went forward with the climb— and completed it unassisted.

“I didn’t have a true idea how truly big it was and what it entailed,” Paddock said. “It was way out of my league.” A film crew followed Paddock and captured the expedition on camera in the 2010 documentary “Beyond Limits.”

The trip to Africa gave Paddock a clue for how to bump the dark rider even more. In Tanzania, he met children with disabilities— some of who didn’t have legs but hadn’t received prosthetics, so they hobbled on their knees. He started the OM Foundation (OMF) to extend his philanthropy beyond Orange County, and help children with and without disabilities around the world. The organization has raised over $1 million since its inception in 2009.

After reaching the top of Kilimanjaro, Paddock wanted to raise more funds and reach a greater sense of peace with himself. He challenged himself with a feat no man or woman with CP had accomplished: the Ironman Kona in Hawaii.

‘Racing his race’

Paddock hadn’t intended on doing the Ironman Kona until he met renowned Ironman World Champion Greg Welch, whom “60 Minutes” once called the “world’s fittest human.” Welch took first place the race in 1994, and famously got 11th place in 1999 despite suffering from what he thought was a heart attack on the route— and he wanted to coach Paddock for the race. The two were introduced by Paddock’s team at Oakley, which had sponsored him for the Mt. Kilimanjaro climb.

“That for me was, like, this guy believes in you?” Paddock said of Welch. “He taught me how to love myself, and he taught me to how love the journey. He would always say, 'Race your race. You’re not gonna win this thing.'"

The training regimen for the 2.4-mile swim, 112-mile bike ride, and 26.2-mile run along the barren lava fields of Kona focused on core and plyometric work for nearly two years, with just one day off a week. Because Welch had been dealing with heart issues, Paddock called on Greg LeFever, a former neighbor in Newport Beach who owns a fitness business, to train him. LeFever and Welch focused on helping Paddock finish the race between the 16:30- and 17-hour marks. Training primarily featured biking and swimming because those rounds were first in the race, and that plan would allow ample time for Paddock to finish the last leg of the race, the marathon.

The one thing Welch and LeFever couldn’t predict was what kind of shape Paddock’s legs would be in following the bike ride, as training didn’t involve the full 112 miles. They had to figure out a way to completely numb Paddock’s legs during the bike portion so they wouldn’t spasm. Because Paddock’s muscles are so tight, nutrients can’t reach them easily, so blood flows more rapidly during cardiovascular exercise.

They decided that, at every 7-mile mark of the bike ride, when buckets of ice are available for racers, Paddock would take huge chunks of ice, and put them down his pants to numb his hip flexor and legs, and then later do the same thing down his back and in his helmet.

“Put it down your shorts, and offend everybody,’” Paddock described Welch’s idea, laughing.

Throughout the race, the ice melted and ran down Paddock’s body, seeping into his shoes and pooling between his toes. His feet would be shredded and bloody when he passed mile No. 112.

A dose of Advil, and a new pair of running socks and shoes later, Paddock was off running. He finished the Ironman in 16 hours and 39 minutes— with 21 minutes to spare.

LeFever said he never doubted Paddock could finish the race on time because Paddock himself didn’t doubt it.

“He’s inspiring,” LeFever, 47, told FoxNews.com. “He’s one of those people that gives off the energy that you want to be around because he inspires you to be better. This guy could have a million excuses not to do anything, but he doesn’t. He never quits; he charges forward. He sets his mind to it, and he does it. It makes you reflect on yourself.”

Inspiring others with CP

Aminian, Paddock’s neighbor and the orthopedic surgeon, said he’s seen firsthand the effect Paddock has on children suffering from CP at events for UPC-OC and other fundraising efforts.

“For them to be able to kind of have somebody to kind of look up to … to kind of demonstrate to push yourself to some physically enduring challenges that usually people without CP are scared of trying, that you’re not that different and that you shouldn’t mentally give up, I think it helps these kids tremendously both with the psychological and emotional sort of nourishment they need and they can’t get from anybody else.”

McConnell reconnected with his younger brother by helping him train in swimming for the Ironman. He said he never expected Paddock to use his diagnosis to effect the kind of change that he has.

“He was always a great person— he had his flaws, but I had my flaws— but would I ever have imagined this? No. I don’t think he would’ve either,” McConnell said. “I think he’s just followed the path that’s been laid out in front of him, and he keeps taking the next step. He just keeps moving forward, and [encouraging others] to try to live their lives without limits and be the best they can be no matter what their challenge.”

Paddock’s next mission is the Team Jake Global Challenge, a two-year effort with Oakley that will award anyone— regardless of disability— who signs up for a half marathon in 2015 and a full marathon in 2016, anywhere in the world, with a signature pair of sunglasses that Paddock designed. The year 2016 marks the 10-year anniversary of Jake Robert’s death.

“It’s a way to honor Jakey— that he never got to walk,” Paddock said. “We’re going to honor someone that impacted my life to appreciate and understand that I do have an amazing gift, and it’s CP, and it’s my leg and to go do a crazy thing like a challenge. And anyone can do it. They just have to make up their mind to do it, like I did.”

To register for the Team Jake Global Challenge, visit teamjakechallenge.org.