Matthew Stepanek (a.k.a. Mattie) was an American poet who was also a peace advocate and motivational speaker. Mattie suffered from muscular dystrophy and left this world a better place at an age of only 13. Before his death he published five best-selling books of poetry, and wrote the lyrics for an album that Billy Gilman performed (Music Through Heartsongs). President Jimmy Carter was especially moved by Mattie and they wrote a book together “Just Peace: A Message of Hope” and he spoke at Mattie’s funeral.

Sources:
http://archive.azcentral.com/families/articles/0710muscular0711.html
“Mattie Stepanek, 13 – Poet and Inspiration”. NY Times/Associated Press. 23 June 2004. Retrieved 09 Oct 2015.
“Review – Heartsongs by Billy Gilman”. AllMusic.com. Retrieved 09 Oct 2015.