There are times when everything is getting you down. Work isn't going well. Perhaps you are burning the candle at all ends. You are mentally, physically, and emotionally exhausted. You are at the end of your rope. Simply put, the straw dropped that's breaking your back. Here are a  few suggestions on handling burnout:
-Try to sleep at night. You are more productive when you are well rested.
-Avoid drugs and alcohol.
-If able to, take a vacation or a PTO day to relax and recharge.
-Speak with a professional to work on stress reduction.
-Call a friend or family member to vent.
-Strive to balance your work and home life.
-Exercise. (I hear it releases endorphins. I'm still trying to find the time!)
Also, speak with management to work cohesively to prevent burnout before it gets the best of you.