Whatever you have been doing that's worn you out, you need to take a break today, get some rest.
Have you been pushing yourself a little too far lately? Perhaps you have partied hard, or maybe you have worked way too many hours. Whatever you have done to drive yourself to this point, it's time to take a break. Admit defeat, your body cant keep going without rest, and do not worry about all you have to do, everything will be just as you left it when you return tomorrow.