The Bestseller "the Secret" is nothing new. It's bringing together old material even from the bible, basically "Ask and you shall receive".
Other classics that were borrowed from
Think and Grow Rich, Napoleon Hill
Creative Affirmations, Shakti Gawain
The Power of Positive Thinking, Vincent Pealel
The message is Have a vision, see it, feel it, believe it to be real.
On a holistic level, this is true.
Our thoughts change how we feel, even how our physical body feels.
Change your thoughts, change your body.
Don't refer to a body part as a "bad" knee, or other part. That's the message that the mind/body receives, and that's what you get.
Change the message, refer to the body part as getting stronger.
Get the picture?