When I first started out teaching, I would get sick nearly every week. The students would come into class on Monday sick and by Friday I was sick and sick the whole weekend. It almost got so bad that I was ready to quit teaching. That was until I started taking a one a day vitamin.
It took about two weeks, but by then I was starting to feel better and after about 6 weeks I realized that I was no longer getting sick every week. It really improved my quality of life.