The more I learned the more terrifying that statement has become. The mind exerts incredible power of the body (and vice versa) and it's much harder to get rid of pain caused by a something in your brain than a cut or a broken leg.
My brain used to have my body act up when I took a certain medication.
I was lucky: Once it got a little ahead of itself and my body started acting funny before I'd even taken the medication.
At that point I knew it was all in my head and never had any more problems with that medicine after that.
This is really interesting! I have a funny reaction to spicy foods: my scalp starts itching. I've notice that the itching can start even before eating when I merely have the spicy food in front of me and I'm anticipating eating it.