Recently while trying to find ways to get out of depression, I remembered seeing a segment on a tv talkshow where they were talking about the science behind feeling good and smiling.
Basically they concluded that our facial expressions directly influence our mood. Frowning for example, is associated in our minds with negative emotions, while smiling or laughing is seen as a positive response. If you force yourself to smile, you can feel better because your conscious mind thinks that if you're smiling, everything's good. I have been trying this myself, simply forcing myself to smile as much as possible and I definitely have noticed an improvement in my overall mood.
I just thought I would share this to see what you guys thought.