Your beliefs create your perception of reality. However, here is a very important point that many positive thinking films like "The Secret" left out. Your conscious mind only controls about 5% of your perceptions of life. Your subconscious mind, which is much more powerful, controls 95% of your perceptions of life.
Therefore, no matter how much your conscious mind is thinking positive thoughts, if your subconscious mind does not have those same thoughts, it will sabotage yo