The sowing and development of the Christian life are different in essence from the sowing and development of natural life, owing to the special character of the Christian life and its relation to our nature.
A man is not born a Christian…[and] since the natural man is injured and opposed by the demand of Christianity…the beginning of a true Christian life in a man is a kind of re-creation…this seed of life (this resolution) is not surrounded in a man by elements favorable to him, and besides this the whole man, his body and soul, remain unadapted to the new life, unsubmissive to the yoke of Christ.
Therefore from this moment begins in a man a labor of sweat–to educate his whole self, all his faculties, according to the Christian standard…in a Christian it is a battle with oneself involving much labor, intense and sorrowful, and he must dispose his faculties for something for which they have no inclination: like a soldier, he must take every step of land…from his enemies by means of warfare…of forcing himself and opposing himself.
~St Theophan the Recluse
Prayerful Life 