"The human body has limitations.
The human spirit is boundless."

Your mind, in other words, is your most important muscle.

"Life is not a journey to the grave with the intention to arrive safely in a pretty and well-preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming: Wow! What a ride!"

Dean Karnazes
Ultra Marathon Man
http://www.ultramarathonman.com/flash/