As a light practitioner of energy manipulation, I can say with a fair amount of confidence that your thoughts really do effect your reality. With so many scientific studies finally surfacing to support this, such as the effect of observation on cells, or the theory of attraction. Having a positive outlook can help improve your health, can give you confidence that you normally wouldn't have had, it even helps you to recognize and approach small acts of 'fate' that you might normally have just passed by.
Even just meditating can have a tremendous effect on your health, giving you more energy and clearing your mind. I think there is a lot that has yet to be discovered about consciousness and its effect on the world around us.