Assuming there is no medical reason as skyDancer mentioned, consider how much of your (and my) behaviors are the result of habit. Start with the habit of smiling. When you smile, other people smile back at you. It becomes catching. Do you have a habit of smiling?
Next is attitude. Do you have the habit of looking at things in their most positive light or do you always see the bad side?
I would suggest you conduct a test for one day: Get up early. Before you go out, look in a mirror and practice smiling (yes I''m serious!). All day long, smile at every person you see. In every discussion, in what you read or watch on TV, seriously look for the bright side. Look for answers to problems and silver linings to things that would normally be a downer for you. Speed up your movements to a brisk pace. Avoid friends and family that have the habit of a "half empty" attitude. At the end of your "test" day, do an evaluation to determine if it's been a better day than the day before.
If you compare a primitive rural tribe living in poverty to the same number of people in Beverly Hills, you will find about an equal distribution of those who are happy and unhappy in both groups. Could it be that our moods are more about how we look at things and react to each other than we realize?
