Singing at the top of my lungs on the top of a hill in the middle of nowhere.

When singing doesn't cheer me up or I have no inclination towards music, it is usually a sign that I might be getting depressed and I take plenty of preventative measures.

Hope you find something to bring you cheer. I would tell you a joke to help things along, but I'm afraid all the jokes I know are so bad that they would have the opposite effect!

Bagpuss