My husband Michael used to never get sick. He prided himself on it. For years, while his co-workers were periodically at home sick with a cold or the flu, he would never miss a single day of work.
Then we moved to Florida. He was exposed to a lot of molds and, perhaps more importantly, a lot of stress. He suddenly found himself getting recurrent sinus infections. His doctor thought sinus surgery was the answer, but alas, while they were fewer, the sinus infections continued. I could see it was not only a physical burden on him but a mental one as well.