It has been documented that nearly one in four people will experience depression at some time throughout their lives. Currently, clinical depression is a disease that is affecting millions of people throughout this country and the world. According to biologists, depression is caused by deficits of certain chemicals in the brain including norepinephrine, dopamine, and serotonin. Depression can also stem from a number of factors including early childhood experiences, parent/ child separation, the death of a loved one, and divorce. There is also a genetic component to depression, putting first degree biological relatives at nearly three times the risk of experiencing depression. People who are depressed become overwhelmed with the feeling of sadness and tend to view their lives in a negative way. For this reason, treating depression is extremely important. There are medications which treat depression, but it has been said that the most cost effective treatment is good old fashioned exercise. Research has shown that regular physical activity has decreased feelings of anger and sadness as well as reduced the amount of tension and fatigue in the bodies of depressed individuals. Throughout this article I will be discussing the following ideas: