Dallas Willard on the Mental LifeThe Divine Conspiracy (San Francisco: Harper Collins, 1998), p. 324.
Now we need to understand that what simply occupies our mind very largely governs what we do. It sets the emotional tone out of which our actions flow, and it projects the possible courses of action available to us. Also the mind, though of little power on its own, is the place of our widest and most basic freedom. This is true in both a direct and an indirect sense. Of all the things we do, we have more freedom with respect to what we will think of, where we will place our mind, than anything else. And the freedom of thinking is a direct order to exercise it. We simply turn our mind to whatever it is we choose to think of. The deepest revelation of our character is what we choose to dwell on in thought, what constantly occupies our mind, as well as what we can or cannot even think of.