Hello, A low mood that doesn't go away can be a sign of depression. low mood lasting two weeks or more,not getting any enjoyment out of life,feeling hopeless,feeling tired or lacking energy,not being able to concentrate on everyday things like reading the paper or watching television,. These are all sign of depression. Life changes, such as getting a regular good night's sleep, keeping to a healthy diet,reducing your alcohol intake and getting regular exercise, can help you feel more in control and more able to cope. activities such as meditation, breathing exercises and learning ways to think about problems differently. Tools such as self-help books and online counselling can be very effective.If this doesn't work consult psychiatrist.