I too am feeling that way night fly. It sux. I have found when I feel that way if I help other people(volunteer time or give the homeless food) stuff like that makes me always feel better.
Bingo.
Go do something not for profit..volunteer, plant a tree, hug a puppy.
All sure fire ways to over come the blahs. The repetitive and competitive nature of today's society can destroy anyone's spirit.
Try reading some Chan Buddism.