I also think of how one person sees a sensation of mild pain. As a kid, most falls, even harsh at times, don't last in your mind. I remember nasty crash on mountain bikes where we would dust ourselves off, laugh and go. The thrill of the action made the pain very secondary. Even the day after, when the injury would hurt a bit more we wouldn't really complain. Because it's part of the pleasure of trying, achieving.

After a certain point, the brain shifts, we're not in growth, we're in maintenance mode and every problems is void of side value, it's just this, a problem.

Maybe it's also because these are self or externally inflicted sensations, compared to surgery for an internal disease.