I think there's something to physical tolerance. My fingers don't seem to burn so much when handling cut peppers.
But there's another side to the equation. The brain naturally equates (Pain == Damage!). Getting past that is more than half the battle. If you watch vids of people eating seriously hot peppers, what you see in their faces is
panic! The brain reads it as damaging and can't figure out how to make it stop.
Now when I eat a really hot pepper I don't think it hurts any less, but there's serenity that kicks in knowing that "this too shall pass".
Or is that the good brain drugs (endorphins)?