Gradually, living with negative thoughts makes you change your beliefs about yourself and the rest of the world. You come to expect loss and disappointment. Self criticism becomes a habit. Your mind begins to distort your perceptions of the world around you, so that you filter out good things and only notice things that are dark and horrible. As these changes occur, you feel your life being pulled farther and farther down. In this state, it is easy to trigger your negative emotions, and you find yourself feeling angry or sad or crying at little things. We will review solutions to these problems in subsequent chapters.
Behavioral psychologists have observed that depressed individuals withdraw from the activities they used to enjoy and avoid being with the people they used to like. They stop going to places they used to like and eating the foods they liked to eat. Their associations become so negative that even the thought of doing an activity that used to be pleasant makes them feel miserable. Behavioral therapy reverses these behaviors and helps you remember how you acted before you were depressed.