No, your illness is not all in your mind. It’s real. It’s physical. But mind and body cannot be separated, and when you influence one, you influence the other. I don’t see any illness as being just physical or just emotional.  For instance, anxiety may be seen as a mental health issue but it also has lots of physical traits such as elevated cortisol levels, racing heart etc.  Chronic pain may be seen as physical, but it is very influenced by emotions and stress. Overall, your body is powerful at healing physically and emotionally when it is calm, so your job is to create calm and allow your body to do the rest.