Transcript for Teenager receives special sweet 16 birthday present from her grandfather
Finally tonight, the perfect example of why grandparents are so great. John donvan with the incredible gift one granddaughter just received. Reporter: This is the one of a kind 16th birthday present one grandfather just gave his granddaughter, about the times they spent together. I thought, kids don't know what they did when they were 1, 2, 3, 4, 5. I thought that would be fun to write down what we did that day. Reporter: It's all there, every day. Like her second birthday party. I rushed to your side and held you. Reporter: With time, she no longer needed watching. So, there is a gap, until this one. It's been a long time since I've written in this book. You're 16 today. When you're old like me, time zooms by. Reporter: A stunning commitment, a rare gift, and perhaps, just the first chapter. I'm hopefully going to share what he did with my grandkids, and hopefully they'll do the same. Thank you so much for watching. "Gma" first thing in the morning. David Muir will be right back here tomorrow night. I'm Tom llamas in New York. Have a great evening.
This transcript has been automatically generated and may not be 100% accurate.