One of the most well documented theories of New Age thought is the Law of Attraction. Simply put, it suggests that you will always encounter, in your life, those things which you think about on a regular basis.
There are many ideas, which have persisted throughout the course of human history, that have been blended to form the theory, so understanding it may take some time and research. However, because this law essentially proposes you can achieve pretty-much anything you want simply by changing your thinking patterns, it remains one of the most interesting ideas to have been championed in recent years.
Though the basic idea itself has come under attack from a number of sources, anecdotal evidence at least, suggests that some correlation between thoughts and future experiences might well exist on some level. If nothing else, the proposal encourages people to consider the overall scope of their thoughts and emotions; and that can be no bad thing.
Many would argue that personal attributes such as the ability to maintain a positive attitude have a great effect on the circumstances of life; and so, at the root, our basic thinking might be found to be the ultimate cause of many positive and negative experiences in life.