[johnnyanmac]

>bounced off the surprise rise of the kerb, and it hurt before I hit the ground.

Sounds like a form of phantom pain. I don't know the exact term but it is a well studied phenomenon. one that, AFAIK, isn't fully understood.

But yes, your brain can very much lie to you. Just look up how much post processing your brain will do to help you see the way you see.

>Sometimes I can switch the pain off on purpose, sometimes I can't.

yeah, we have chemicals in our body to do that. It doesn't turn off pain automatically because it is in fact a good thing to realize when you're bleeding out of your leg. It only turns that off for you semi-voluntarily if your brain involuntarily determines (again based on other chemicals) that GTFO is more beneficial to survival than tending to your wound. I'm not going to say it's impossible to train these excretions of chemicals. I will argue that this is probably something you can train for years to do and fail, though.

There's so much about our bodies that still eludes the brightest minds. Even a function as basic as sleeping and why and how it benefits us is still not fully in our understanding.