A lingering sub-clinical level of depression is common for the unemployed, especially when the time period out of work is prolonged. Worry, frustration and guilt take a toll on all of us: they sap our energy and our enthusiasm, and eventually make us sick.
Confirm to yourself that you are taking all the right actions to obtain employment. Then squeeze in some extra time to take care of yourself.
Try to fit in a short but regular exercise break each day to improve your mental outlook. Use an evening walk with your significant other as a stress reliever and also a chance to process your daily activities and frustrations. Make sure you eat regularly and choose foods that will build up your health, like lots of vegetables and proteins. Don't forget to take vitamin and mineral supplements that will help your immune system ward off that enveloping stress.
Take 3 or 4 relaxation breaks throughout the day - even 5 minutes of calming deep breaths, stretches, or brief meditation can temporarily remove you from the toxic stress of being without work. It will keep you mentally strong and gently release the nervous energy stored in your muscles so that it is available for job search activities.
Running yourself down, both mentally and physically, is counter-productive and will negatively affect your self-presentation, a critical aspect of obtaining work.