Burnout is a state of physical and emotional exhaustion. It can occur when you experience long-term stress in your job, or when you have worked in a physically or emotionally draining role for a long time. You can also experience burnout when your efforts at work have failed to produce the results that you expected, and you feel deeply disillusioned as a result.
You might be experiencing burnout if you:
Feel that every day at work is a bad day.
Feel exhausted much of the time.
Feel no joy or interest in your work, or even feel depressed by it.
Feel overwhelmed by your responsibilities.
Engage in escapist behaviors, such as excess drinking.
source:
http://www.mindtools.com/pages/article/recovering-from-burnout.htm Have less patience with others than you used to.
Feel hopeless about your life or work.
Experience physical symptoms such as chest pain, shortness of breath, sleeplessness, or heart palpitations. (Make sure that you see a physician about these!)