This is an excellent video showing the Research From Dr. Masaru Emoto. His work clearly demonstrates the power of the mind. Thoughts and emotions can have a strong effect on your perception of the world. I find the video very relaxing as I watch it.
Hypnosis is an excellent tool for focusing the Unconscious Mind to habitually think positive. By unconscious I mean the part of the mind that is not conscious. You can't think of everything at once, we are not wired that way. So through self hypnosis you can train the unconscious mind to think positive. You learned to tie your shoelaces, so why not learn to think positive?