Transcript for Hand transplant recipient, doctor get surprised by Captain Sully: Part 5

Reporter: 21 arduous months after Jonathan Koch first felt sick, a moment that would have been inconceivable at the start — he awakes from surgery with a newly transplanted left hand. I was told that an hour after surgery you were moving fingers. It was Jennifer’s birthday when I got out of surgery, and she said, I just want one thing. I just want you to move one of your fingers. Or I think you said move your thumb. I think I can move it. That’s amazing! And I didn’t think there was any chance that I could. But I thought about it, and it moved. What a birthday present! Yes. It was the best birthday present. Then all of the sudden this guy comes on. And that’s where it began. Every hour, something would come back. Doc, will I be able to play the piano after the surgery? It was incredible. Reporter: A new hand, yes. But what kind of new life lies ahead? Remember, he also lost fingers on his right hand, and a leg to that insidious disease. It’s in my heart that if you, you know, you set your mind to something and you’re willing to get through the pain, anything is possible. Thank you. Boom! That’s awesome. About one week in he’s gripping a tennis ball and throwing it. What? Reporter: From the opening serve, his doctor says, it was advantage Koch. Unbelievable. So, better than expected? Better than expected. Next thing you know he’s — he’s got this little video that he shows me where he picks up a glass of water and he takes a drink. And he goes, ahh. Jonathan has met, or in the vast majority of cases, exceeded all of my expectations. The classic one was, I told him Jonathan, it’s gonna take you maybe a year and a half to two years before you can tie your shoelaces. At two months he sends me a video of him tying his shoelaces Reporter: That moment loaded with symbolism – for the man who’d told us he first learned to tie his shoes in that basement – under the duress of his dad. You don’t have a lot of patience for this. No it’s — Because you said I – you know, my doctors are telling me I’m a year ahead of schedule but I don’t feel like I’m a year. Well, I don’t ’cause I’m just doing what’s in front of me. Reporter: For months now, he’s put more in front of himself than many would. Now you have full extension. Remember you didn’t in the beginning? That was the most difficult one. Reporter: At UCLA, an exacting rehab regimen to build up the hand itself. And at the gym. Dude, good job. There’s constantly something new on the horizon that we’re trying to accomplish. Reporter: An exhausting workout schedule to restore his whole body. Ten, one, come on. Seeing him do new things after his hand transplant, quite a few of them brought tears to my eyes. Ready, go. Reporter: But maybe the greatest reward of all, doing anything with his daughter Ariana. I’ll get you next time. How cool is it to be able to work out with Ariana again? Oh, I love it. You know, doing those things now with her are just extraordinary. Reporter: Like in February, a milestone that seemed implausible. They attend Ariana’s last high school father-daughter dance. You made it to a father daughter dance again. I did. Father-daughter dances are amazing, and Ariana was incredible. She took care of me the whole night. Okay, let’s do this. Reporter: But I got to share a pretty special thrill with him too. Perfect. A rally on his beloved tennis courts. Yes! How’s it feel? It feels good, I just can’t really feel my grip that well yet. Reporter: As if playing tennis alone isn’t amazing enough, the natural righty had to learn to do it left handed. Yes! Yeah, I’m not great. But I am working on it. And I’m having a blast relearning tennis. Good job. You’re amazing. Reporter: It’s not without issues, his heart and lungs are not at the levels they once were. And like any transplant recipient, there is a lifelong looming possibility of E rejection. Curiously, Jonathan says he’s lost a lot of his taste for food, and he overheats a lot. So he carries a fan, even during our interview. I’m just going to cool down one second. Yeah, sure. Reporter: But wherever Jonathan goes, he is a living breathing inspiration. I feel very much that I’m, you know, the test pilot for this. You know, that my hand is my hand but it’s really all of ours. Reporter: And speaking of pilots, remember the one who’d inspired the whole world with his heroism? I have a little surprise for you Reporter: Well we asked. Am I about to be pranked? Reporter: And he agreed. Come on in. Reporter: To pay Dr. Azari a surprise visit. Good afternoon! Cool. Dr. Azari. Reporter: Captain sully. Evacuate! Reporter: The high-flying hero who makes a down-to-earth cameo in our little Hollywood movie. I cant tell you how many times I’ve cried watching that movie. That was an incredible day for amica. I think at a time when we all needed it. It gave us all hope. Oh, my goodness. Jonathan, how are you? Good, how are you? Jennifer, it’s a pleasure to meet you. Pleasure to meet you. It’s pretty remarkable isn’t it? It is amazing! It’s been an incredible experience. As something happens almost every day that changes it. It’s amazing how complex the human body is. Shake? That’s lovely.

This transcript has been automatically generated and may not be 100% accurate.