Rocky Walker always considered himself the picture of health. He said that he walks between eight and 10 miles a day, and that's just when he's at work. 

For the past five years, he's been a chaplain at Mount Sinai Heart on the Upper East Side. It's his job to give cardiac patients of all faiths, and their loved ones, both spiritual and emotional support during what can be an extremely difficult time.

In November, the tables turned for Walker after he received a grim diagnosis.

"I knew something was very wrong. I had chest pains, like, the worst things I'd ever heard doctors describe. Like an elephant standing on my chest," Walker said. 

The next day, Walker sought treatment at Mount Sinai Heart and learned he had a pulmonary embolism, a large and often-fatal blood clot blocking a major artery in the lung. 

Dr. Umesh Gidwani treated his friend and colleague during his time of need.

"It was difficult because he's not just any patient to me. He is the provider of much support and sustenance to our patients as well," Dr. Gidwani said. 

It’s been six months since the ordeal, and Walker is doing well. Doctors were able to break up the clot with blood thinners and without surgery. In fact, after just a few days in recovery, the chaplain returned to his job.

According to the chaplain, the experience has had an impact on his work, but not in a bad way.

"The time that we spend in their presence, it is a big deal, and for us, our day as providers is going very fast, but for them, it's not moving that fast, so it became more important for me to make sure that I slow down and work at their pace," said Walker.

Patients like Wilbert Wilson, who is waiting for a heart transplant, said it is a philosophy that he appreciates.

"Sometimes, we all get a little down on ourselves, especially me, and in the position that I'm at right now, I need all the love I can get right now," Wilson said.

After his experience, Walker said that he is now more qualified than ever to provide advice and support to heart patients.