"The great Law of the Universe, however, is just this - that what you think in your mind you produce in your experience. As within, so without. You cannot think one thing and produce another. If you want to control your circumstances for harmony and happiness, you must first control your thoughts for harmony and happiness, and then the outer things will follow. If you want health, you must first think health; and, remember, thinking health does not mean merely thinking of a healthy body, important as that is, but it also includes thinking peace and contentment and good-will for all, for, as we shall later see in the Sermon, destructive emotion is one of the primary causes of disease. If you want the spiritual unfoldment and growth in knowledge of God, you must think spiritual thoughts - God thoughts - and give your attention, which is your life, to God rather than to limitation."
-Emmet Fox, The Sermon on the Mount