Here's an enjoyable article from 2001 about the famed "Marathon Monks of Mount Hiei" by the London Observer's James Davis. It was posted on Facebook by July Oconer, one of the Finishers and Sponsors of the 1st Bataan Death March 102K Ultramarathon Race, then picked up by 57-year-old marathon runner Jovenal “Jovie” Narcise, aka the indefatigable Bald Runner. These toughest of spiritual athletes are members of Buddhism's Tendai sect. Davis writes:
The ultimate achievement is the completion of the 1,000-day challenge, which must surely be the most demanding physical and mental challenge in the world. Forget ultra-marathons and so-called iron-man events, this endurance challenge surpasses all others.
Only 46 men have completed the 1,000-day challenge since 1885.