We are all John Nash
Under the favorite movie category of a blog questionnaire I briefly considered A Beautiful Mind. The movie portrays the John Nash's recovery from paranoid schizophrenia, partially through pure force of will - the discipline of daily disregarding paranoidal thoughts. This could be seen as a metaphor for all of us. Certainly sin is a sickness, a form of insanity (Frank Sheed emphasizes this with the title of his book: Theology and Sanity). We see things in a false light, through colored glasses (see Matt 16:23). Thus we need to constantly discipline our thoughts with respect to what is real.