Furthermore, the Fathers highlight that the less man has submitted himself to the pains of asceticism, the more he must undergo involuntary suffering; this is not some kind of chastisement for his negligence, but rather a providential gift from God in order to permit man to receive the spiritual good things that would otherwise remain inaccessible to him. They insist on the fact that without effort and even without suffering, it is impossible for man not only to be purified from the least passion, but even to acquire the least virtue, to pass from the state of a fallen creature to that of the “new creation”.
St John Damascene notes: “Conversion, the passion from what is contrary to nature to what is according to nature, is accomplished by asceticism and sufferings.” St Isaac the Syrian repeats this many times: “The commandments of God are fulfilled in afflictions and torments”; “the cause of virtue is the narrow path of affliction”; “the virtues are linked to afflictions. Whoever withdraws from afflictions inevitably withdraws from virtue. If you desire virtue, accept to be bruised.”
~Dr Jean-Claude Larchet (Therapy of Spiritual Illnesses vol.2 p.263)
Prayerful Life 