That's a question to which Sandy resident Luke Marti now knows the answer.
Marti would undergo excruciating pain and struggle through a fight so difficult, he doesn't even know how he found the power to succeed.
Marti, 34, said he found out exactly what he was made of last week in a tunnel covered by a crushing wall of mud that had fallen on him under a pool his company was installing in Centerville.
"I had this weird impression that I didn't have that long to live," he said. "I was able to eventually free myself."
Marti was covered by heavy debris from the waist down. He said the pain was tremendous as he wiggled his way out with his shattered clavicle and pelvis and broken ribs. His spleen was severed and he was bleeding internally.
Read more with our partners at the Standard-Examiner.