Hey, excellent. How many kilometers were you able to cross without moving one inch further? :) It takes a special kind of mindset anyways. And persistence and stubbornness not to speak about physical ability at all ...
Marathons are a way to go too, great. I was a marathoner once and I intend to be again.
I did 84.1 miles (135km). I was aiming for 85 miles. I still broke the record by 4 miles, so that was good. Here's a video of the last couple minutes..