Mulan: You certainly sound overwhelmed. Are you able to reduce the workload without affecting your primary responsibilities? Does your overall job description require so much to be on your plate all at once? How does your desk look? Is it chaotic? Can you prioritize. Maybe take a day just to tidy up and maybe it won't look so unsurmountable.
There are many people who try to keep busy in order to push out a thought or a situation that is causing angst in their private life. I call it running. Keeping too busy steals the time your spirit needs to gather it's wits and relax. Meditate on your private life and see if there's an unresolved matter you've been putting off. Work is good therapy but if it dominates your being you become a slave to it.
Take a nice bubble bath or sit in the garden and have a cup of tea. Turn of the cell and Blackberry and don't answer any e-mails for a day. Give yourself a break from the daily labors. Any unfinished business of the heart and soul must be completed. Put yourself first and the joy of your job will return.
Regards, M. Poirot