Why Do Reiki Masters Get Sick?

Time after time, I have heard people say that Reiki, Qi Gong, or other forms of complementary energy therapy must not work, because the people who perform them sometimes get sick.  "Why do they get sick, if they are full of this magickal energy?" they ask. 

I'd like to talk about this fallacy, about why it doesn't make sense, but also about how--even though these methods don't make anyone bulletproof--they do help people to stay healthy, and to heal faster and more easily.