How 9 friends saved a woman waiting for a heart transplant Amy Silverstein shares her story in "My Glory Was I Had Such Friends."

 -- Amy Silverstein credits a group of nine friends with saving her life when she had her second lifesaving heart transplant at age 50.

The friends, who came from different parts of Silverstein’s life and from around the country, cared for Silverstein, in her California hospital as she waited with a failing heart for her transplant to come through.

The friends -- whose heroic efforts Silverstein, 53, documents in her new memoir, “My Glory Was I Had Such Friends” -- made sure she never spent a moment alone, even creating a spreadsheet calendar to organize their time in the hospital.

“You feel blessed to show up, and it's a gift for us in a certain way, to be able to show up for her,” one of the nine friends, Jane Shepardson, told ABC News.

The friends, some of whom were strangers to each other, said they thought it was a “very real possibility” they might lose Silverstein even as they spent time making her laugh and giving her spa treatments at the hospital.

“[We] absolutely had to reckon with the possibility that we were leaving and we might not see Amy and it might not come through," said Robin Abrams.

Silverstein, who now lives in New York City, was herself counting down the days until her suffering would end.

"I had a big number up on the wall," she said of the days she waited for a transplant to come through.

The "Sick Girl" author underwent her first heart transplant at age 25 when she was in law school.

“I was in law school and I found it hard to walk to class and went to the doctor, and they found out I was in heart failure,” Silverstein recalled. “The doctor said that after the transplant, if I got an organ, I would live maybe 10 years, at best.”

Silverstein surpassed those expectations by living with her first donor heart for more than two decades. When she underwent her second transplant in 2014, Silverstein was able to walk down the hospital hallway just one day after surgery.

Silverstein’s donor heart came from a 13-year-old girl.

“I was told that this young girl, who I know nothing really about, but she was an athlete and she makes me want to run and I can feel her as I run,” Silverstein said. “She gave me new life, not just life but new life.”

She added, “I never imagined that I would ever feel this well.”

Silverstein’s group of friends, the same nine women who saw her at her weakest moment, said they notice the new life in their friend today too.

“We were at a gathering about a year after this heart transplant and I looked over and saw Amy dancing with like so much color in her face,” recalled Shepardson. “It stopped me in my tracks and I started to cry.”

She continued, "We never could have imagined that she would feel that good, look that good and be the healthiest she'd been in her entire life.”

Silverstein's memoir about her friends' resilience and friendship has been acquired by J.J. Abrams' production company for a limited TV series, according to Deadline. "My Glory Was I Had Such Friends" is available now.