There’s a joke among recreational runners that those who tackle thirteen-point-one miles are only “half crazy.” Marathoners, however, and ultrarunners who take on 26 miles or more at a time are a different breed altogether. It takes a special kind of crazy to willfully run that long and that far.

The scientific term for what mere mortals call “crazy” — that will to push through the pain — is resilience. A new study shows it might come from highly trained interoception (in-tuh-ro-ception). Interoception is the ability to evaluate internal needs, like thirst, and then take appropriate action, like drinking water. It draws on an area of the brain called the insula (in-SUH-la), which influences self-awareness and emotions.

Well, scientists at the University of California at San Diego and the Naval Health Research Center wanted to investigate interoception and how it influences the extra edge in Marines, Navy SEALs and adventure racers … types who power through stress and physical exhaustion every day.

So the researchers assessed Navy SEALs and 10 control subjects’ ability to read happy and scared faces. As expected, the SEALS showed more right insula activity in the brain and were faster at detecting facial expressions.

A second test involving adventure racers showed the trailblazers, too, had increased insula activity during the same emotion detection test and less during mild suffocation, showing a better response to stress.

These results suggest staying in touch with what’s going on both inside and out can boost your ability to resist defeat. But for average joe athletes born without this evolutionary advantage, take heart: You can still build resilience. Channel positive energy by chanting a mantra, know that the pain will pass and keep your eyes on the prize. Now put aside your doubts, push through the pain and take that hill!