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 that 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.
Check out the above video to learn the seven universal principles of manifestation.