Their beliefs about themselves are twisted, and their beliefs about the world are equally distorted.  Unfortunately, they are not aware of the twisted and negative bias in the way they think.

If you take a metal bar and subject it to pressure, the metal eventually distorts.  If you take a mind and subject it to high levels of stress, the mind often produces distorted and twisted thoughts.  Unfortunately, the mind under stress believes that the twisted and distorted thoughts actually reflect the world in which they live.

Twisted  thinking isn't a reflection of the world.  It's a reflection of a mind operating under high levels of stress.  If you relieve the stress, usually the twisted thinking subsides, and you realize that your twisted thoughts are abnormal; they don't accurately  reflect who you are or the world in which you live.

Distorted, negative thoughts are a warning telling you that there is a problem.  When negative and twisted thoughts take over, you must heed the warning and immediately take steps to rectify the situation. 

Don't believe your twisted thinking.  Closely examine such thoughts under the light of day, and it won't be long before they cease to be a problem.  You learn to ignore those thoughts, because you know that you are not listening to the voice of truth that can set you free.  You are hearing the sound of a stressed out mind slipping into negativity and depression.

Excerpt from :

Zero Tolerance To Negative Thinking : Good-by Depression - Hello Positive Mind

David J Abbott M.D.