Joe Rogan once recalled the time when he believed he may have killed someone when he knocked somebody out as a teenager.
The 56-year-old is one of the most recognisable faces and voices in the UFC as a color commentator for the MMA company.
He also hosts one of the most popular podcasts on the planet called the Joe Rogan Experience which has a deal with Spotify for an estimated $250m.
In his youth, Rogan became interested in the martial arts and when he was 14, he took up karate and later taekwondo a year later.
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Rogan also became an amateur kickboxer, but he retired from competition after suffering frequent headaches and a fear from sustaining more serious injuries.
Rogan became the UFC's color commentator in the early 2000s after the company was purchased by new president Dana White, and he has been in that position ever since.
On one episode of his podcast, Rogan recalled when he was aged 19 and taking part in a taekwondo fight, the same age when he won the US Open Championship in the martial art.
And he revealed that in a martial arts encounter, he knocked out a competitor who he did not see get up and was taken to hospital.
It was this episode that made Rogan question his continued involvement in martial arts, though he now practices jiu-jitsu, due to the potential either he or someone else could lose their lives.
He said: "One time, in a fight, in a martial arts fight, I knocked this guy out. He never got up. And I started thinking, 'that could be me'. Because they took him away to the hospital.
"And I went back to talk to my instructor. And he had heard of the fight and he said to me, 'I heard you had a really good knockout' in this thick Korean accent. 'Yeah', I said… I go, 'it was really scary because he never got up. I thought he was dead'.
"And he goes, 'sometimes they die'. And he just walked away. Like he used to train troops in Vietnam. He was, like an intense guy. And he said 'sometimes they die', holy s***. 'That could be me, I could die'."
John McDougall