I follow the Surly (bike company) factory blog. I own one of their bikes and love it. They seem like an eccentric but fun group of guys (and gals) and generally spin a good yarn in their posts.
One write-up in particular that I look forward to every year is the report on the Arrowhead 135.
It's a 135mi bike race*. In January. In northern Minnesota.
Read that again and ponder the implications. People do crazy things in the name of fun.
Anyway, this years' article has appeared, so here's a link to it. I thump my chest and say that I do Triathlons, but the things I have done are nowhere near the depth of endurance and tolerance for discomfort as this. /salute.
*Actually, you can bike, run, or (assuming there's snow) ski the course.