All sickness is a form of unforgiveness.

Into eternity, where all is one, there crept a tiny, mad idea, at which the Son of God remembered not to laugh. In his forgetting [to laugh] did the thought become a serious idea, and possible of both accomplishment and real effects. (T-27.VIII.6:2-3)

Remember, the separation began not with the tiny, mad idea, but when we remembered not to laugh at it and took it seriously instead. Therefore if we can look at our ego—even better, if we can look at our decision for the ego and not take it seriously, we will have undone the ego. Thus, we are not asked to give up taking vitamins; we are asked to give up taking our taking vitamins so seriously, which happens when we judge ourselves for taking them. Likewise, we take the ego seriously when we feel good about something working in the world and then feel guilty about feeling good. That is the problem. Remember, the problem was not the tiny, mad idea; it was taking it seriously. This means the problem is not your special relationship, anxiety, depression, financial or physical situation. The problem is taking any of that seriously, which means giving it power to take away the peace of God. That is what taking it seriously means. Forgiveness means being peaceful at the same moment you are aware of your resistance to doing the workbook and learning this course; being peaceful about holding on to judgments about people, and holding on to grievances of the past and bringing them up every once in a while, whether they are grievances against yourself or other people. The miracle, as well as forgiveness, means that you can look at all of that and not make a big deal about it. Forgiveness is not really about undoing your guilt; it is about looking at it and not taking it seriously. That undoes it. Miracles versus Magic Part V

Remember the section, "I Need Do Nothing" (T-18.VII). So you have an allergy, which is a nonexistent problem. That is why you have an allergy: to distract your real analyst, Jesus—who does not analyze—from helping you with the real problem. If you try to work at what the meaning of the allergy is, why you have the allergy, why it is happening now instead of yesterday, and all those kind of things, what are you doing? You are taking the tiny, mad idea seriously. This course is so simple. Jesus says it over and over again. This is simple, yet we make it so complicated. Do not fix your ego, or your symptoms, and do not analyze your symptoms. Be peaceful. If you choose the right teacher, you will be peaceful, whether you have an allergy, cancer, or an automobile accident; whether the sun has just come up or not. It will not make any difference. You will be peaceful. That is the lesson. Remember, the problem was not the tiny, mad idea; it was taking it seriously.  In The Song of Prayer, Jesus tells us not to make the error real: "Do not see error. Do not make it real" (S-2.13:3-4). What is the error? The error is the ego.  Do not take it seriously. Do not fight against your ego. Look at it, understand why you are holding on to it, but do not do anything about it.
The point of Lesson 79 "Let me recognize the problem so it can be solved" and its companion Lesson 80 "Let me recognize my problems have been solved" is that if my problem has been solved, why do I have to solve it all over again? I would only try to solve the problem of my ego if I believed the problem were not solved. What I have to do is accept the fact that the problem has already been solved. I do not take a problem seriously when it has already been solved.  Miracles versus Magic Part VI

"All material means that you accept as remedies for bodily ills are restatements of magic principles" (T-2.IV.4:1). This is referring to interventions such as taking medicine, going to a doctor, using what is considered New Age medicine like acupuncture, or dieting, taking vitamins, exercising, standing on your head, or whatever.

"This is the first step in believing that the body makes its own illness. It is a second misstep to heal it through non-creative agents" (T-2.IV.4:2-3).

"It does not follow, however, that the use of such agents for corrective purposes is evil. Sometimes the illness has a sufficiently strong hold over the mind to render a person temporarily inaccessible to the Atonement" (T-2.IV.4:4-5).

So suppose I am sick and I know what the Course teaches—that all sickness is a form of unforgiveness. But I am not ready yet to forgive you truly, to change my mind about you. I know ultimately that is what I must do, but in the meantime I am still in a lot of pain. The most loving thing I can do for myself at that point then is to see a magician, whether it is a doctor, an acupuncturist, a healer, etc., who can alleviate my pain. Whatever I believe will help me is what will help me. Thus going to a doctor is a form of magic that will take away my pain. It will not take away my guilt or unforgiveness, but it will at least take away my physical pain. And going to the doctor can also be an expression of joining. Basically I am saying to the doctor, "The only help that I can accept from God, at this point, is through you." In turn, the doctor is saying to me, "The only help that I can give you from God, at this point, is through my magic." So we are both joining, sharing a common purpose of helping and being helped. And that is healing. But because I am too afraid of the healing, I believe that what helps me is the form of magic that the doctor is giving me. What It Means to Be a Teacher of God Part XXV

Taking the tiny, mad idea seriously_YouTube Excerpt from FACIM "A Course in Miracles" Workshop

People question why Ken Wapnick died. Maybe because Cancer is nothing. We are figures in a dream.  Maybe the lesson is nothing is real.