It's like Henry Ford said "If you think you can or you can not, either way you are correct." Our beliefs and thoughts affect our values which in turn affect our attitudes which in turn affect our action or inaction which in turn affect our experiences which ultimately affect our circumstances or our reality.  If we are constantly entertaining negative thoughts like, "I'm depressed, I'm stupid, I'm never going to get a better job, I'm in the wrong place at the wrong time, my life sucks, I'm not good enough, I'm not lovable etc..." We are not motivated to take a positive action, in fact,  most likely we are stuck in inaction which is going to lead to proof of your negative beliefs. Thus creating a self fulfilling prophecy of what we don't want.  This is a vicious cycle and one that needs to be addressed (at the root) at the level of thought and belief.   Romans 12:2 Do not conform to this world, but be transformed by the renewal of you mind.