It is actually really important to keep on thinking about something or dreaming to achieve something in life.if you stop thinking or dreaming then the positive hopes start dimimishing and the question that arises is what are you doing with your life?the blankness starts prevailing and you become dull because you dont even try to think leave aside thinking logically.To overcome this, you need  a source of new thoughts like reading a book may bring new thoughts which at this point can trigger the thinking process provided the topic is interesting for you.