The way that we think can impact on our mood and result in depression. In particular, there is a strong link between the thinking style of rumination and depression.
Rumination describes a tendency to compulsively focus on the symptoms and causes of your unhappiness and distress. It is the need to constantly ponder on the things that are causing you distress without taking any positive action to identify and make changes. It is that point at which you are wallowing in unhappiness with the mistaken belief that by focusing on your distress and your past failures you will find a way out to resolution and happiness.