Humans react to extrenal stimuli.  When there are physical changes in the enviornment, such as changing climatic conditions, the body responds accordingly. Just as the body responds to change in the physical environment, it also responds to the stress brought about by changes in life's circumstances  If the stresss is severe, it can eventually lead to illness. Some of the events that cause stress are listed below:

1. Major illness in the family.

2. Death pf a spouse

3.  Retirement from work

4. Child going to college

5. Vacations

6. Taking out a loan for a major purchase

7. Changing schools

8. Change in eating habits

9. Marriage