i have seen it with my own eyes, more than once
how you could 'know' such a thing is beyond me, but lets just say you do.
what about my friend who was suffering from joint aches so debilitating she had to reduce the hours on her job and was having problems paying her bills. i noticed she dranks lots and lots of diet soda with aspertame in it. i told her that aspertame could cause her symptoms and she told me i was nuts and said she would stop drinking it just to prove me wrong. well, in a about three day her pain had lessened, and in two weeks she was able to go back to work. was that "all in her head"?
and what about my friend who cut off the tip of his finger and it turned gangrenous and the doc who had sewn it back on wanted to amputate it. my friend said no, let me try a few things. so he started stopped the antibitics and all the meds he was on, and started drinking huge amounts of fresh wheatgrass juice. the very day he started drinking the wheatgrass the finger began improving. the more he drank the better it got, when he stopped because he had to take a short trip, the finger again began turning blue. he started with the wheatgrass again, and it started to get better again. eventually it turned pink and bran new, completely HEALED. was that "all in his head"?
i could go on and on. i have seen wholistic health do amazing things for people, i have seen it literally save people's lives with my own eyes. so you can doubt it all you want, but i have seen it first hand and i know. and these lame "all in your head" claims are silly at best, and certainly are totally unscientific. but maybe you don't believe in science?