To try to discredit my theory, you're going to tell me "What about physical reaction? People don't say 'Ow' and jump away from the THOUGHT of pain, but of the actual pain." Well, you're partly true here. But let's look at the thought of pain first. How many people do you know that have to get a shot and before the needle is anywhere near their skin, they start shaking or moving the feet quickley or saying "Owey Owey Owey Owey......?" Those are instances of people reacting to the thougth of pain. To address physical reaction to pain, I bring in a new word: Shock. When you get a paper-cut, your immediate reaction is to move your hand (or whatever it is you cut) away from the paper. That's shock, not pain. Ever notice how it takes a half second before you say "Ow" or have any other physical reaction to a paper-cut? That's because your brain is letting your hand and body know that "We were just cut. That hurts."
More proof that pain is mental isn't that hard to find. Emotional pain. Everyone has lost someone close to them. I've lost my mother and a best friend, so I know about emotional pain. When you know that someone close to you is sick or has just passed away, there's no physical inflictions upon your body, but don't you hurt anyway? Doesn't your stomach start knotting up and cramping and don't you feel like vomiting?
If you aren't convinced by now that pain is mental, let me know your argument and I will address it when I update this essay.