ATLANTA (FOX 5 Atlanta) - Music brought Josiah Martin and Britni Ruff together.
But, something much bigger now connects the 34-year old Atlanta gospel singer and 22-year old Spelman College senior.
"I feel like this is something that was placed on my heart," Ruff says.
Because, for the last decade, her new friend had been watching his health slip away.
"I have a genetic kidney disease called FSGS," Martin says. "It destroys your kidneys."
By 2013, in his late twenties, Josiah's kidney function went into a free fall.
He learned his kidneys were working at just 5% capacity.
Martin began dialysis, and stopped touring, because it was too difficult to juggle travel with the 4-hour dialysis treatments he needed three times a week.
"I got put on the transplant list right away," Martin says.
Then, he waited, for 5 years.
The whole time, Martin knew the same disease that took his oldest brother's life at 29 could very well take his.
"So it was hard on everybody, trying to process what I was going through, and worried about if the outcome would be like my brother's," he remembers.
Britni Ruff knew her friend needed a kidney, but it wasn't until the fall of 2017, when she heard his new song, that Ruff realized how dire his situation had become.
"He was, like, 'Lord, it's going down. I'm getting ready to die. I just need you to make it okay,'" Ruff says. "And, I was like, 'I've got to go get tested for him tomorrow, because if anything happens to him, and I never tried to see if I could do anything, I wouldn't be able to forgive myself.'"
So, Ruff reached out to the Emory Transplant Center, and learned she was the same blood type as Martin.
In July of 2018, Emory called Martin.
"They said they had a donor, and it was a living donor," he says.
But Emory couldn't tell him who his donor was, and neither could Britni Ruff.
"I didn't think he would let me do it," Ruff says. "If I would have told him, he would have told me, 'No, don't do it. You're too young.
"I guess I didn't want him to get in the way of himself.'"
Still, keeping a secret this big was hard.
"Literally, every day, I was, like, 'I'm going to tell him!' I drafted so many text messages. I dialed his number."
But somehow, Ruff waited until August 17, 2018, their surgery day.
At 5 in the morning, inside Emory University Hospital, the two friends met in a waiting area.
"It was kind of, like, 'There he is!' Ruff says.
"I heard somebody calling my name and I'm was, like, 'Oh, what are you doing here?'"
Martin thought Ruff had come out to support him.
"And I was, like, You're getting my kidney," she laughs.
They were just minutes from surgery.
"It was a whirlwind after that," Ruff says. "Like, once I said the words, everyone was crying all of a sudden. It was such a beautiful time."
Beautiful, and bittersweet, because Josiah Martin couldn't help thinking about his big brother.
"I was mentally processing that I was going to get something that my brother was never able to get," he says.
Their surgeries went smoothly. Afterwards, with her mother and Josiah's sister at Britni's bedside, she allowed herself to cry. But there was no regret.
"I would 100% recommend it to anyone who is willing to do it," Ruff says. "I would do it again if I could. I don't know that they'd let me, so I won't!"
The next day, she and Josiah each rang the transplant bell, to single the end of their journey.
Seven months later, Martin is touring again, set to release a new album.
"I feel amazing," Martin says. "To have someone give life out of their own life is beyond anything that anyone could ever imagine."
Britni Ruff says helping her friend, helped her grow, too.
"It feels good," Ruff says. "You get to walk with your head a little higher afterward."
To learn more about living kidney donation, and paired kidney exchanges, visit the National Kidney Registry, at www.kidneyregistry.org.