The point is to have a positive attitude and to know that life is good. If you emit a positive attitude to the world around you then you will also attract positive people and experiences. I've found it to be entirely true. I gained a new perspective on life and existence after reading that book. Calling it a myth and hating on it will only attract more negative things to you.

Also this is not an original idea from the book. Just another method of describing an ideology that has been discussed and practiced for thousands of years.