Troubles and illnesses don't just happen. There are causes. We know today that many illnesses are caused by our poor eating habits. In the past, many plagues were caused by poor hygiene. But there are also non-physical reasons for our illnesses and problems. Some is often because of out subconscious belief that we have done something that deserves punishment, so we invite illness and difficulties to plague us. Often though it is what is best known as karma: what goes around, comes around; what you do unto others, others will do to you and what you send out into the universe will be reflected back to you.