I have, like many of you, experienced stressful times, from illnesses to accidents to family deaths. Stress can be caused by a number of things, from positive to negative. Even a birthday party, which is considered a positive experience, can be stressful (who to invite, preparing the food, cleaning up, buying gifts, etc). Each change, whether a marriage, buying a house, selling a house, a divorce, going to school, taking a trip, graduating, having children, a death of a family member or spouse - these are all stressors. And they have different levels of stress. For example, if your spouse dies, that is a heavy-duty stressor and carries more weight than a birthday party. Also, there is stress from family members that can spill over into our lives.
I read once that if you have more than 3 stressors in 6 months, then the likelihood of becoming ill is much higher. Stress can affect our health. It happened to me, and I've been very careful not to add more stress than I can handle within a six month period. It seems to have worked so far (keep my fingers crossed).