tonight, our robin roberts is changing the world again. She showed us all the powerful possibility of a bone marrow transplant and how you can become a donor. And then, this morning, she showed how... See More
tonight, our robin roberts is changing the world again. She showed us all the powerful possibility of a bone marrow transplant and how you can become a donor. And then, this morning, she showed how you return from a struggle stronger than ever. Her co-anchor, josh elliott, was right beside her and she is with me. So great to be with you this morning. Reporter: So good to see you, diane. It was beautif. As you know, as well as anyone, diane, it was -- robin was going to be back, it was going to take her months, and it was going to ask everything of her, all that she had to give, but today, after so public and painful a road and with a touch of nerves, she made it all the way back. Five minutes to air. There you go, baby. Yeah! Five. Four. Three. Hi, it's robin. And I have been waiting 174 days to say this -- good morning, america! Reporter: What no one could see in front of the camera, what we saw behind the scenes, of a morning we'd all longed for. Faith, family and friends have brought me to this moment, and I am so full oude. Reporter: A day of celebration after an arduous trek that began last june, when she first told us. It is a rare blood disorder that affects the bone marrow. Reporter: To a few months lae saw her in treatment, receiving her sister's precious bone marrow. This journey is as much about the mind as it is about the body. Reporter: We prayed with her. We sang. We watched in awe as she fought. I know my former teammates at southeastern, they'd be like, two? Two pounds? That's it? Yeah, that's it, but it's one more pound than I did the last time. Reporter: She willed her body to match her spirit, all leading up to today. How was it? Like riding a bike. Reporter: So, shaky and bumpy and all over the road? You know, my doctor said to me a few days ago, he said, it's time to take off the training wheels. It feels good. And I just wanted to come back to work. Reporter: Her doctors reminded us that she's still walking the path to recovery. Today is the dress rehearsal. I don't care who the If you're not well enough to go, you're not going. Reporter: Record bin's got a busy few days ahea her, with the oscars and an interview with the first lady. I have to say, physically, i feel -- I have good -- I have better platelets than sally ann right now. Reporter: Her sister quite literally with robin now, every step of the way. It was the easiest thing in the world to be a donor, and I'm just so amazed at your strength. Reporter: And at long last, robin's remarkable journey had finally taken her home. I know everybody, nobody should touch her. Nobody should touch her, but i get to. I got special. Welcome back. Thank you. Reporter: Thanks, partner. Thank you. Reporter: And when she left, diane, we saul swore that oath of friends and family that her fight would be our fight and then we were all left to wait and to hope and she did what she's always done. She fought and she won and so did we all. And she was so back. What is she talking about training wheels? Come on. Two-wheeler. Reporter: Come on. She's in the fast lane if ever there was one. For sure. And I want you to know on friday, I'm going to sit down with my friend and we will talk about everything as we always do. And it's part of a special edition of "20/20," robin's journey, at 10:00 p.M. Eastern.
This transcript has been automatically generated and may not be 100% accurate.