If something seems to have gone wrong with your body, the temptation is to believe it is has reality and truth to it.
ACIM: "Temptation has one lesson it would teach in all its forms wherever it occurs. It would persuade the holy Son of God he is a body, born in what must die, unable to escape its frailty and bound by what it orders him to feel."
This is the temptation, the ego's attempt to get us to BELIEVE that the sickness is true, the damage is real, the suffering is really happening, something really has gone wrong. It's all part of the belief in sin.
Our challenge then is to do the opposite of be tempted, which is to seek Atonement, by learning to UNDO the false perceptions which are causing you to see an illusion as something more than just an illusion.
If you have come to believe that your sickness is a REAL SICKNESS, then you're got a problem far more deceptive than the sickness itself. You not only have "a sickness" but also a sickness of perception, a mental illness, in which you believe that an ILLUSION of sickness in the body is actually reality and truth. You are having perceptual hallucinations. You are not seeing correctly.
To UNDO these false perceptions, you must be willing to re-frame what you thought was sickness and see it in a different way. You must become able to see it in such a way that it "registers" with you as completely "false". You need to come to recognize it as and be convinced that it is, nothing more than an ILLUSION and NOT a reality.
This does imply, and means, that all forms of sickness are FICTIONAL, and all forms of sickness are merely fake images which you have MADE in an attempt to put on a show of sickness really happening. Whatever the sickness allegedly is, it is not a REAL sickness, it can only be a fake sickness.
In God's reality, there is no such thing as real sickness. Sickness is separation from God. And one expression of such a sickness, which believes an illusion of separation is real, shows up as physical sickness. That means that in how you're looking at this sickness, your belief in it, your seeing SIN in it, your belief that it's really happening and has weight and is tangibly real and NOT an illusion, IS your sickness because it's an expression of separation from HEALTH, which is separation from WHOLENESS or God.
It is tempting to believe the body's signals, like, well, I have this thing going on in my body and it's doing stuff to me and I don't know how it got there and it's a threat and it has power over me and I don't want it. If you believe this, then you WILL start trying to fight with it and to get rid of it.
But you're trying to get rid of an ILLUSION which YOU yourself believe is really there, so your BELIEF in it is actually you VALUING it, giving it credit as truth and reality, which means you will KEEP it. And then you will be attempting to fight against your own belief that it is real, which is an attempt to keep it, so your war against it will just be a state of conflict between yourself and yourself.
To become single-minded and whole you can't be believing in it while trying to get rid of it. You must UNDO your belief that you have a REAL sickness. You must convince yourself in any way possible that it is NOT a real sickness, it is NOT really happening, it does NOT have truth to it, you are NOT at the effect of it, it does NOT have power over you, and it is not REAL at all. It's completely fictional. It's an illusion, not a reality.
It's a made-up, faked, artificial, PRETEND SICKNESS, which you invented. You are the one who has fallen for the temptation to believe in it. You are the one who put it there. You are not a victim of it. And you do have power over it. And in truth, because it IS an illusion, it is completely FALSE, you do NOT have a real sickness, there IS NO SICKNESS, and the sickness is ALREADY GONE! The truth of all sickness is that it has not really happened at all.
Seeing that about the sickness is seeing the Atonement, which means you are forgiving or overlooking the sickness. You overlook sickness by overlooking the temptation to believe that the ILLUSION of sickness is the truth. If the sickness has literally not happened because separation has not happened, and if it is recognized as completely FALSE because of your recognition of what the TRUTH is - God's truth, then you will REMEMBER that this "sickness" simply cannot exist at all.
That's the kind of place where your mind needs to get to in order to heal. That's the kind of perception that you need to have. Illusory things are actually RECOGNIZED as illusory. The way that illusions strike your perception is then very different to how they seemed or what they meant when you believed in them. You will EXPERIENCE them as false, have a sense even of the falseness of them. A sense of not believing in them and regarding them as not true. That's the healing of perception which is your mind UNDOING the belief in the sickness so that it can be recognized as not existing.
Thus you recognize it has disappeared because it never really existed, it's already gone, it never even happened in the first place, you do not believe in it, there is no truth to it, it is completely false, unreal, and God did not create it. Therefore it simply cannot be happening and is not happening.
This reveals that you are actually quite a powerful creator who has literally MADE UP a sickness and presented it as an IMAGE of sickness, showing up in the FORM of your body, and that nevertheless this is not really there. You are a maker of dreams! You brought the illusion of a sickness into being and you can just as much demolish that illusion by becoming willing to see it for what it is. It is not truth, it is fictional. All sickness is fictional. There is no such thing as a real sickness of any kind.
You must learn to withdraw ALL of your belief in the FANTASY of "sickness" that this world holds dear. You must decide that you will never believe sickness is real ever again. You will not be tempted by the illusion of it, you will not see it, you will recognize it as a LIE which you do not fall for or want, and which is always completely false. Sickness is NOT THERE. It must go because it is already gone. Collapse the sickness and get all belief in sickness out of your life forever.
Believing that the truth is true, and only the truth is true, will give you the power to work miracles.