When Charlie St.Cyr-Paul agreed to become a guide for a disabled runner, he was as much in the dark as Chris Lancaster is daily.
St.Cyr-Paul attempted to find information online about what being a guide entailed. Nothing.
So the music producer from Orlando drove to Lake County and ran with his eyes closed, a visualization exercise in reverse.
"You should try it sometime," St.Cyr-Paul said. "In about five seconds, I wanted to throw up. I was so nervous and terrified, and I kept doing it and doing it.
"I wanted to get to the point where I could understand what is going on, and I couldn't. It was just too much. I only can imagine what it must be like for someone who can't see."
Lancaster, visually impaired because of a hereditary condition called retinitis pigmentosa, knows.
Since St.Cyr-Paul guided Lancaster for the first time in 2014, they have become attached by far more than the shoelace looped around their fingers during races. They've run the Walt Disney World Marathon together for three consecutive years.
"It was nothing I ever expected," said Lancaster, a father of two girls who lives in Dahlonega, Ga. (about an hour north of Atlanta) "I thought it would just be another guide who would help me with the race, and it would be the end. Charlie was different because he wanted to be there. He wanted to help me achieve my goals."
Guides can be arranged for runners of various disabilities, including -- but not limited to -- those with autism, post-traumatic stress disorder and social anxiety, said Chris Hughes, Track Shack special events coordinator. Finding the right match of guide and runner can be as formidable as running for four hours, making St.Cyr-Paul and Lancaster appreciative of what they have accomplished.
They completed the Dopey Challenge -- running a 5K, 10K, half marathon and marathon on consecutive days -- during the Walt Disney World Marathon Weekend in 2014. With St.Cyr-Paul, Lancaster finished an Ironman triathlon last year in Louisville, Ky., and several half Ironmans.
They have plans to do a half Ironman in Augusta, Ga., in September and Lancaster's second Ironman in Panama City Beach in November. Both intend to run the Boston Marathon in April, although Lancaster, 39, will be accompanied by another guide.
"When Charlie does something for Chris or for another (disabled runner), there is a great sense of satisfaction, knowing he helped that individual excel," said Jeff Cuddeback, a triathlon coach who has worked with St.Cyr-Paul. "It's a little bit different feeling than going out and doing it (for) yourself. It is not less. It is just different. They are both really good."
No statistics are kept on how many visually impaired runners complete marathons, but organizations such as Achilles International and United in Stride help connect guides with those requiring a partner. Race organizers, such as runDisney and Track Shack, can assist as well.
United in Stride is operated by the Massachusetts Association for the Blind and Visually Impaired, where Kyle Robidoux serves as director of volunteer and support group services.
"Just the population in general, there are so few folks who complete a marathon," said Robidoux, who is legally blind. "Just straight up, a marathon is a tremendous feat, regardless whether you are sighted or visually impaired."
Lancaster said a good guide for a disabled runner must have a strong personality and be willing to take charge. The guide also must be faster than his partner, so he can adjust his speed accordingly.
St.Cyr-Paul, 44, qualifies on both counts.
"I find much more joy in the whole journey when I am part of helping someone else reach his goals," St.Cyr-Paul said. "My races and my goals were really quite trite and selfish. I enjoy the guiding and feel like that has been a calling for me."
Said Jennifer Lancaster, Chris' wife: "(Charlie) is a great motivator when Chris hits those moments of doubt. I guess they call it the runner's lull. Charlie helps him to get through that."
Lancaster will compete in his 10th marathon this weekend, not all with St.Cyr-Paul. He crossed the finish line at the 2015 Disney World Marathon in 3 hours, 26 minutes, 6 seconds -- about 23 minutes faster than his time two years ago.
He and St.Cyr-Paul have traveled to so many races, but this weekend, they will navigate a course they know well.
Even if one of them runs in the dark.
"It is nothing more really than a great friendship," St.Cyr-Paul said. "He can't see, and I am a pain in the (neck). We both have our challenges."
They get through them.
Together.