QUOTE : For you do by nature want to do what you take to be good for you; reason reveals that what is in fact good for you is acting in a way that is conducive to the fulfillment of the ends or purposes inherent in human nature; and so if you are rational, and thus open to seeing what is in fact good for you, you will take the fulfillment of those ends or purposes to be good for you and act accordingly. This may require a fight against one’s desires and such a fight might in some cases be so extremely difficult and unpleasant that one might not have the stomach for it. But that is a problem of will, not of reason. It doesn’t show that the rational thing is not to struggle against one’s desires, but only that doing the rational thing can sometimes be extremely difficult and unpleasant.