I'm a fire-eater. There is some technique to fire-eating, but most of the practice goes into learning that one's mouth is wet enough, most of the heat goes up enough, and cutting the oxygen leg off the fire triangle (it's now a fire tetrahedron, but I learned fire-eating a long time ago) with one's mouth really does put the fire out.
It took watching a professional whom I trusted do it -- a lot of trust and a lot of practice -- before my first reaction, when my mouth started to burn from the lit torch in my mouth, was to put the torch deeper in my mouth, close my mouth around the torch and put it out.
Handling fire seems like a superpower. There are whole seminars and self-help jive centered on fire-walking, which is hustled as "mind over matter," or "empowerment" but is really just counterintuitive physics. As long as the fire walk is set up right and you keep moving, you can even hope and pray to be burned, while yelling counter-self-help slogans such as "I do not have any power to do this" and "universe, please burn my little piggies," and you'll be fine.