Self-denial is healthy.  Self-indulgence will eventually sicken the whole person ending in spiritual and perhaps physical disease and death.  When the self insists on what is not good for itself, one must say no to the self.  The self often wants to express itself contrary to the teachings of Christ.  We find that we cannot follow the teachings of Jesus without intentionality and self-denial.  All of this is for our ultimate good and well-being.

“Having lost all sensitivity, they have given themselves over to sensuality so as to indulge in every kind of impurity, with a continual lust for more.” Ephesians 4:19 (NIV)