We tend to look at what we don't have in life instead of what we do...we are agreeing with the enemy when we line up our thinking the world's way. We are called to "be in the world, but not of it", meaning we are to separate ourselves not just from "worldly" activities but our thoughts as well. The only way to transform your thoughts is by reading God's Word... you cannot apply the world's methods (positive thinking, astrology, hypnosis, etc.) to your life and expect to get God's results.
Romans 12:2, "Do not conform any longer to the pattern of this world, but be transformed by the renewing of your mind. Then you will be able to test and approve what God's will is--his good, pleasing and perfect will."