You should train yourself: Even though I may be sick in body, my mind will
be free of sickness. That’s how you should train yourself…. And how is one
sick in body but not sick in mind? There is the case where an instructed
noble disciple … does not assume the body to be the self, or the self as
possessing the body, or the body as in the self, or the self as in the body.
He is not obsessed with the idea that “I am the body” or “The body is mine.”
As he is not obsessed with these ideas, his body changes and alters, but he
does not fall into sorrow, lamentation, pain, distress, or despair over its
change and alteration. (Similarly with feeling, perception, mental
processes, and consciousness.) This is how one is sick in body but not sick
in mind.
– The Buddha, Tricycle Fall 1997