It's not really a secret. That information has been around for a long time. She simply brought it up again. This is the same idea held by James Allen (As a Man Thinketh), Napoleon Hill (Think and Grow Rich), and more recently than them, Shakti Gawain (Creative Visualization). I also found Neville Goddard's teachings to be very similar in nature. So no, this is not a new theory.
More interesting reading in a similar vein is the Celestine Prophecy and the subsequent books by James Redfield.