I heard Muhammed Ali on NPR's "This I Believe" program the other day. Parkinson's Disease, which he's had since 1984, has ravaged his ability to speak, so he asked his wife to read most of it. He does speak at both at the beginning and the end of his essay.
I have used the quotation at the top if this page for several years now because it so perfectly embodies my own determination to walk 60 miles. Ali is a natural poet, was known for his rhymes before boxing matches, and more can be found on his site, http://www.ali.com, which is worth checking out. Here's his quote of the day:
"Service to others is the rent you pay for your room here on earth."