Typically people with ME/CFS/FMD get worse if they push themselves. The key to recovery is rest first and foremost. The symptoms of FMD seem to be a protection mechanism by the brain, and pushing through the symptoms just make it worse.
I've cured myself. Who have you cured? No one I'm sure.
To me, it seems it's a theory to compensate for medical imaging technology that has far too low resolution. Doctors hate admitting that they don't know what's wrong, so instead they claim that the patient is crazy in politically correct terminology with an excessive number of syllables.
Structural tissue damage starts at a molecular level that cannot be seen by medical imaging technology. The fascia alone is too thin to be imaged at all, and so is completely ignored.
Biochemists have delineated in explicit detail how tissue breaks down at the molecular level. And they can reverse it. We need to start listening to them more.
I had attempted all the psychiatric treatments recommended to me. None of them ameliorated the physical symptoms.
Then I discovered what physical compounds my body was missing, and the physical symptoms AND mental symptoms resolved. So yes, the mind and body are not separate. They are constructed out of the exact same basic building blocks.