Try to calm down and think about things critically, Honestly I my self thinking pessimistically alot when things don't go my way or what not. I find the key is to discover something that you enjoy enough to loose your self into, and that can help you relax and lesses the strain of your problem. For me its music, when I get some nice Ambient Techno going I can relax and start thinking clearly about some of the more complex issues in my life.