"The one thing I do remember about transplant day is when Dr. Giralt is standing over me and … I'm looking up at Dr. Giralt, and he's looking down at me, and we're the only two in the room. I don't hear anybody else, I don't see anybody else. I just see Dr. Giralt. And he starts inserting the syringe into a port I have in my chest. And I remember... seeing tears. He has his mask on, but I remember seeing tears in Dr. Giralt's eyes. And I can see that his mouth is moving, and he's saying something," Roberts recalled.
He was praying. "Let God do his work and it will work,'" Giralt explained. "To me, it does capture the real sense of the moment ….The way this finally evolves is a whole joint of events that may be beyond our control, and is in the control of a power above us. And our role is to do the best we can, with the instruments that we have."
While the procedure took just five minutes, Roberts' road to recovery had just begun. As the new cells began to set up shop and get ready to regenerate, Roberts was in complete isolation.
"There was something that was very... isolating about being in isolation," she said with a laugh. "That it's just you. But it's also a way of really... my grandma used to always say, she loved the mornings. And she loved quiet time. Boy, did I have a lot of quiet time. And I learned to appreciate it, because I've always been just going non-stop."
The first 30 days when the bone marrow takes hold is a tough time in treatment, according to Dr. Gail Roboz, the New York-Presbyterian Hospital/Weill Cornell Medical Center oncologist who is treating Roberts. There are mouth sores, weight loss, diarrhea, hair loss and food doesn't taste good.
"There was a time after the transplant that the back of my throat, I was told, looked like I had swallowed a blow torch. That's how raw, that's how red, that's how painful my throat was. I couldn't swallow, I couldn't eat. It was very difficult to, to even drink," she said.
Roberts slowly began to regain her strength. After a month, she was eating solid food again, and then 30 days of isolation, she took her first breath of fresh air and was able to return home. That marked a major milestone in her recovery and she continued to will her body to match her fighting spirit.
READ MORE: Next Steps in Robin's Recovery
Watch the full story on "A Special Edition of 20/20: Robin Roberts' Journey" TONIGHT at 10 p.m. ET