Your body is telling you that you're pushing too hard. A change of pace, no matter how short, will give you a new outlook on your situation. It's on the busy days that you should take a few minutes for yourself. Most people need at least seven hours sleep each night . You deserve a break.
Constant work can mean constant stress.
Balance your life with some recreation such as swimming, skating, running, or reading. Then, go back to your work with a relaxed and open mind. Sometimes it helps to take your mind off yourself and your immediate situation. Doing something for somebody else no matter how small will make you and the other person feel good. There are lots of fun and easy ways to relax.