It takes a bit of work to prep for such an attempt. Ulrich states he went on several 18 mile runs - dragging a tire on a rope to help increase core strength.
Ulrich shares several memorable ultra moments, like the time he hallucinated that a woman in a silver bikini was rollerblading in front of him, or when a farmer in Ohio unloaded some buckshot when Marshall jogged past his property late at night.
At one point during his run across America, Ulrich stopped at an emergency room and had his body MRI'ed. He wanted to make sure the pain he was encountering wasn't life threatening. Seems that the docs noted he had a raging case of plantar fasciitis, but that fell into the flesh wound category. The doctor recommended rest, so Ulrich calmly stated that he would cut back to 40 miles the next day.
That's pretty much how this story rolls from encounter to encounter, mind master Ulrich staying on top of his game whatever the circumstances. Some of his greatest challenges came from a lack of human interaction; his life on the road was 17 hours running, 4 hours sleep, and a few hours for showers and eating. He craved simple conversations that was about anything - except running.
I'm not advocating that most mortals can read Ulrich's book, watch the accompanying DVD, then conquer similar feats. But we can vicariously enjoy the journey and understand that where the mind goes, the body will follow.