Teacher donates kidney to fellow teacher: 'Best decision of my life'

For two New Jersey teachers, it's back to the classroom this September -- but not after an uneventful summer.

Three months ago, Michael Daneman, a K-8 computer science teacher at Saint Leo the Great School in Lincroft, New Jersey, gave his fellow teacher the "gift of life."

Daneman donated one of his kidneys to his colleague Lauren Crupi, a sixth-grade and seventh-grade language arts teacher, on June 1, a decision that he said only took him about a day to make.

"It was Jan. 1. [Lauren's husband] posted on Facebook the whole story and that they were looking for a donor," Daneman recalled to "Good Morning America." "I took just about one day to think about it. I actually researched it most of the day and then I reached out to Lauren's husband, Paul, and he gave me some more information to look into and I pretty much got the ball rolling from that."

Crupi told “GMA” that she has a rare genetic disease called MUC1 kidney disease, which is a type of autosomal dominant tubulointerstitial kidney disease named after the gene, MUC1, that is mutated in individuals who have the condition. According to the National Organization of Rare Disorders, MUC1 kidney disease can lead to kidney impairment in the teenage years or young adulthood and usually requires dialysis or a kidney transplant later on.

"I was on medication to slow the progression of the disease as much as they could. And then, at the end, the last couple of months before [the] transplant, when I was really feeling my worst, [I had] a lot of fatigue [and was] out of breath. I had a really gray coloring. I was anemic so I was cold all the time," Crupi recounted.

Crupi said after her husband posted on Facebook, Daneman was one of the first people who reached out to inquire about donating a kidney.

Daneman found out by April -- after another potential donor didn't work out -- that he was a match for his co-worker and didn't hesitate to get testing done and get ready for surgery.

The students and the staff at Saint Leo the Great rallied and gave the two teachers a big send-off at the end of the May, ahead of their donation and transplant surgeries.

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"They sent us off in such an amazing way, starting with breakfast, to surprise blankets, to a huge clap out with pom poms and everyone clapping and cheering us on as we were leaving at the end of the day," Crupi recalled. "It was like, 'Oh my gosh, it's really happening.' … We really were sent off in the most uplifting and positive way."

On June 1, Daneman and Crupi both underwent surgeries at NewYork-Presbyterian Hospital in New York City, and afterward, they both woke up and said their first thoughts were to ask about each other.

"My family and I can never possibly thank [Daneman] enough and will spend the rest of our life trying," Crupi said. "I owe all of this to him and in my life, all the future moments that I will have I owe to him. … We're eternally grateful for the gift that he gave me."

Meanwhile, Daneman couldn't be more pleased to help a friend out during a time of need and described donating a kidney as the "best decision" of his life.

"My catchphrase since surgery [has been], 'Best decision of my life.' Because there's really no drawbacks for me. There was a week, a month of pain. It's totally worth it," Daneman said. "I'm just grateful that everything worked out. I'm happy that my friend is healthy and that she's back to work."

The two teachers say they're closer than ever too.

"She's my sister now. I mean, I already have three sisters. Now we've got four. Her whole family is my family now," said Daneman.

"He's stuck with us," Crupi continued. "My family's never going to stop bothering him."

Crupi and Daneman say they're both doing well post-surgery and encourage others to consider organ donation.

"I feel amazing," said Crupi, who is also a mom of two. "It feels so great to be back in the swing of things, able to do it thanks to Mike. It feels awesome to be back in [a] routine, back at it with my kids."

"If you are healthy and you have healthy kidneys and you can change someone else's life, I hope that's what [others] consider doing for someone else, because it's the greatest gift you could ever give," she continued.

Added Daneman, "In the process, I've learned how long people can wait on a transplant list ... and that really opened my eyes. People can wait for years on the transplant list. So, I really hope that people take this and research it and see if they can maybe help somebody."

Saint Leo the Great Principal Caroline Fitzgerald said she "couldn't be happier" for Crupi and Daneman.

"Mike just went out of his way with the ultimate … gift of life," Fitzgerald said. "That is just amazing and something that I hope our students take with them and realize that, yes, there is good out there. There truly is, and they are a true example."

Said Crupi, "This school and community is so special. From the students, the staff, the parents, the colleagues, everybody who works here is so special, and we felt it a ton. … If I didn't work here, I don't know where I would be right now."