"If you believe, you will receive whatever you ask for in prayer."
"What things soever ye desire, when ye pray, believe that ye receive them, and ye shall have them."
These two quotes mirror, very closely, the ideas talked about in The Secret. They're actually in the book, itself.
"For as he thinketh in his heart, so is he..."
This is a dominant idea in many personal development works that state: "Our lives become what we think about most."
I find it very interesting that some of the core ideas of self-improvement and success (clarity of desire, belief, thought manifestation sculpts our lives.) are found in the Bible.
Was the Bible the first large scale self-improvement work?