Optimism is infectious, so if you can't seem to cure your blues yourself, try hanging out with a more positive crowd. Notice other people's reactions to crises and how they cope. Listen to the way they talk and interact with others. You might even ask how they maintain an upbeat attitude. Make a list of the specific differences in their behavior and yours. When you see that others can indeed be happy in spite of their troubles, you'll have more faith in your ability to do the same.