Duane 'Dog' Chapman was hospitalised earlier this month after complaining of chest pains. He was diagnosed as having a pulmonary embolism.
The shock news comes just a few months after his wife Beth died from cancer back in June.
Duane, the star of Dog The Bounty Hunter, appeared on The Dr. Oz Show to talk about the diagnosis.
The 66-year-old revealed that his attitude towards death has changed since he received the news.
In the clip, he tells Dr Oz: "I said, after Beth left, I'm not afraid to die... I take that back. I'm not afraid to [die], but I don't want to."
Although the survival rate is high, a pulmonary embolism can be life-threatening. It happens where a blood clot travels to the lungs, blocking the artery and blood flow to them.
But since he had the diagnosis, he has has overcome his fear of death.
He continued: "Oh I was afraid to die. I said 'please let go of my heart, honey. Quit squeezing my heart.'"
Dr Mehmet, who hosts the chat show, said: "You're a ticking time bomb.
"You're not going to be here with the heart the way it is right now. Fear of death is normal.
"I'm surprised you don't fear death when you're chasing after convicts. But when you run away from doctor, that means you have to do your own doctoring."
He originally thought that his chest pains were down to having a 'broken heart'.
The doctor then said that he is on the road to recovery.
Beth, who was 51, had been placed in a medically-induced coma after being treated for cancer over the past few years.
Duane 'Dog' Chapman confirmed that Beth had sadly passed away on 26 June, announcing in a tweet: "It's 5:32 in Hawaii, this is the time she would wake up to go hike Koko Head mountain. Only today, she hiked the stairway to heaven. We all love you, Beth. See you on the other side."
She had been battling cancer for several years and was taken in to the ICU at the Queen's Medical Center in Honolulu, Hawaii, on Saturday.
Beth was first diagnosed with throat cancer in September 2017 and later that year she was given the all clear. However, it later came back and spread to her lungs.Featured Image Credit: Sony