Only the foolish think that suffering is evil. A sensible man knows that suffering is not evil but only the manifestation of evil and healing from evil. Only sin in a man is a real evil, and there is no evil outside sin. Everything else that men generally call evil is not, but is a bitter medicine to heal from evil. The sicker the man, the more bitter the medicine that the doctor prescribes for him. At times, even, it seems to a sick man that the medicine is worse and more bitter than the sickness itself! And so it seems at times to the sinner: the suffering is harder and more bitter than the sin committed. But this is only an illusion – a very strong self-delusion. There is no suffering in the world that could be anywhere near as hard and destructive as sin is. All the suffering borne by men and nations is none other than the abundant healing that eternal Mercy offers to men and nations to save them from eternal death. Every sin, however small, would inevitably bring death if Mercy were not to allow suffering in order to sober men up from the inebriation of sin; for the healing that comes through suffering is brought about by the grace-filled power of the Holy and Life-giving Spirit. 

Blessed is the man who uses his sufferings, knowing that all suffering in this brief life is loosed on men by God in His love for mankind, for the benefit and assistance of men. In His mercy, God looses suffering on men because of their sins – by His mercy and not His justice. For, if it were by His justice, every sin would inevitably bring death, as the Apostle says: “Sin, when it is finished, bringeth forth death” (James 1: 15). In place of death, God gives healing through suffering. Suffering is God’s way of healing the soul of its sinful leprosy and its death.

St. Nikolai Velimirovich

They tell the story that on one occasion, while the blessed Anthony [St. Anthony the Great] was dwelling in the desert, thoughts of dejection and despair rose up in his mind, and he was in deep gloom of thought, and said to God, "Lord, I wish to live, but my thoughts will not permit me to do so. What will I do in my tribulations to be saved?" And he came a little nearer [to the town] from the place where he was, and he saw a man who was like to himself, and was in his own form, and he was sitting down and twisting palm leaves into ropes ; and this man rose up from his work, and prayed, and afterwards he sat down again and continued his work, and then he stood up once more, and prayed. Now the man was an angel who had been sent from God to correct and to admonish the blessed Anthony, who afterwards heard him say to him, "O Anthony, do you also do this and live"; and when Anthony heard this, the blessed man had great joy, and afterwards he did as the angel had done, and lived.

from Sayings of the Holy Desert Fathers

Be merciful to your soul in her infirmities; excessive strictness distracts from repentance and leads to depression and despair.

St. Ignatius Brianchaninov

Have confidence in the compassion of our Creator. Reflect well on what you are now doing, and keep before you the things you have done. Lift up your eyes to the overflowing compassion of heaven, and while He waits for you, draw near in tears to our merciful Judge. Having before your mind that He is a Just Judge, do not take your sins lightly; and having also in mind that He is compassionate, do not despair. The God-Man gives man confidence before God.

St. Gregory the Great