SALT LAKE CITY - As the World Trade towers collapsed in 2001, Mark Mahan rushed into the streets, where ash and debris filled the air and the clothes of those around him.
"You could see just men and women caked in white,” Mahan recalls.
A successful finance worker for Deutsche Bank, Mahan once worked less than a block away from the World Trade Center in New York.
"They were gorgeous buildings," he said. "When you were upstairs in the restaurant, they had narrow windows, but you could feel the building sway and see the shifting skylines."
Now, his view looks over Salt Lake City from his medical office at the University of Utah.
"It changes everything," Mahan said of the 9/11 attacks. "Honestly, you have a different perspective with what's going on in your life. You're forced to think about your mortality."
Mahan grew up in Tulsa, Oklahoma, but through a good luck, and hard work, found his way into Princeton. Unlike many of his fellow classmates, Mahan said he didn't come from money, but said the environment and the success that surrounded him in college made a job on Wall Street seem alluring.
"I loved my paycheck," Mahan said with a slight laugh. "It was a psychology rewarding phenomenon to get paid like that for what you do."
But Mahan said as the days and weeks passed after the attack, the financial growth in his bank account wasn't enough to fulfill him emotionally as a person. He said he wondered what needed to change.
"Am I going back to work?" He asked himself. "You have to go back to work. Then you're wondering, why am I doing what I'm doing? Is this what I want?"
That question led Mahan to contemplate a career change to do something meaningful and something that could help others. Dr. Mahan then spent four years going to medical school and another seven years doing neurosurgical training, but, four years ago, he officially became a neurosurgeon.
He said it was a decision that didn't sit well with some of his former coworkers. He said one friend's dad offered a harsh warning.
"He doesn't travel in the sphere that you and I can comprehend, that's how wealthy he is," Mahan said of his friend's dad. "He looked at me and said, 'You're doing the dumbest thing I've ever heard.'"
Somewhat ironic, considering what Dr. Mahan does now. Over the past few years, he's specialized in reconstructive neurosurgery, which helps rewire the pathway of communication from the brain to other body parts. Dr. Mahan said the job leaves him feeling much more fulfilled, though admits it has its challenges.
“When I come home, I’m like, 'Yeah, there are a lot of tough times, but I helped people today. This is what my life is about.'"