St. Benedict of Nursia ca. 480-547

Hence, brethren, if we wish to reach the very highest point of humility and to arrive speedily at that heavenly exaltation to which ascent is made through the humility of this present life, we must by our ascending actions erect the ladder Jacob saw in his dream, on which Angels appeared to him descending and ascending. By that descent and ascent we must surely understand nothing else than this, that we descend by self-exaltation and ascend by humility. And the ladder thus set up is our life in the world, which the Lord raises up to heaven if our heart is humbled. For we call our body and soul the sides of the ladder, and into these sides our divine vocation has inserted the different steps of humility and discipline we must climb. (Rule of St. Benedict Chap. 7)

Saint Isaac the Syrian (d. 700)  

[When you are] afflicted by illness and agonies of the body, be vigilant over yourself and consider the multitude of remedies that the true Physician sends to you for the health of your inner man. God brings illness for the health of the soul. Ascetic Discourse 8

Saint John Chrysostom (347–407)

The physician is not only a physician when he orders baths, adequate nourishment, and when he orders the patient to walk through flower gardens, but also when he burns and cuts…Thus knowing that God loves us more than all the physicians combined, we need not worry nor have any need to ask him to justify the means he employs. Rather, whether he wants to be indulgent or severe, let us abandon ourselves to him. For by either of these means, his desire is always to save us and to unite us to himself. Homily on the Paralytic

Saint John Climacus (6^th Century)

Properly speaking, afflictions are not evils; but they appear to be such in the eyes of those who are struck by them for their own good…In fact, however salutary iron and fire may be for treating a gangrenous wound, and however charitable the hand of the doctor may be who uses them, in the eyes of the patient their use in an evil. Every teaching seems bitter at the time to those it is intended to form, just as the apostle declares: “For the moment all discipline seems painful rather than pleasant; later it yields the peaceful fruit of righteousness to those who have been trained by it” (Hebrews 12:11). Conferences VI.3.

Saint Gregory of Nazianzus (329-390)

Let us respect the illness that accompanies sanctity and offer homage to those whose sufferings have led to victory; for it may be that among these ill persons there is hidden another Job.

Oration XXIV.34.

St. Ambrose of Milan ca. 339-397

And what is the intention of the Scripture which teaches us that Peter fasted, and that the revelation concerning the baptism of Gentiles was made to him when fasting and praying, Acts 10:10 except to show that the Saints themselves advance when they fast. Finally, Moses received the Law when he was fasting; Exodus 34:28 and so Peter when fasting was taught the grace of the New Testament. Daniel too by virtue of his fast stopped the mouths of the lions and saw the events of future times. Daniel vi.-vii And what safety can there be for us unless we wash away our sins by fasting, since Scripture says that fasting and alms do away sin? Tobit 12:8-9

Who then are these new teachers who reject the merit of fasting? Is it not the voice of heathen who say, Let us eat and drink? whom the Apostle well ridicules, when he says: If after the manner of men I have fought with beasts at Ephesus, what advantages it me if the dead rise not? Let us eat and drink, for tomorrow we die. 1 Corinthians 15:32 That is to say, What profited me my contention even unto death, except that I might redeem my body? And it is redeemed in vain if there is no hope of the resurrection. And, consequently, if all hope of the resurrection is lost, let us eat and drink, let us not lose the enjoyment of things present, who have none of things to come. It is then for them to indulge in meats and drinks who hope for nothing after death.

Rightly then does the Apostle, arguing against these men, warn us that we be not shaken by such opinions, saying: Be not deceived, evil communications corrupt good manners. Be righteously sober and sin not, for some have no knowledge of God. 1 Corinthians 15:33 Sobriety, then, is good, for drunkenness is sin. (Epistle 63: 16-18)