Archimandrite Gabriel Bunge: Despondency over one's calling

 We cannot admire sufficiently the perspicacity with which Evagrius unmasks as a temptation of acedia all secret doubt about the authenticity of one’s calling, of one’s decision to follow a certain type of life, whether it be as monk, priest, or married man. These thoughts infiltrate slowly, and with time they hollow out inner confidence, like water dripping on stone. Considered from the purely human point of view, in every decision, in addition to the high-minded and authentic, there are all types of merely foregrounded and entirely ignoble motives at play. But God Writes straight with crooked lines, since he calls sinners, not the righteous. Each “calling” turns out to be, in a retrospect of belief, an ultimately grace-full election.

+Archimandrite Gabriel Bunge, from Despondency: The Spiritual Teaching of Evagrius Ponticus on Acedia, Chapter 4 Manifestations of Despondency.

St. Theophan the Recluse: On Christian grief

 Although we must shed tears in our grief, let us do this in a Christian way, not as the heathen who have no hope. Let no word of complaint come from our lips, nor any feeling of despondency darken our hearts. To weep and grieve is a very human thing, but to give way to despondency and despair, complaint and criticism, is satanic. So let us dissolve grief in hope, so that a new warmth and tenderness will be born in our tears: this will not be the kind of weeping that burns and torments, but one that melts the heart and pours out comfort.

+St. Theophan the Recluse, from a sermon preached during a severe drought during his service as bishop of Tambov, quoted in The Heart of Salvation: The Life and Teachings of Saint Theophan the Recluse, Chapter 4 Theophan's Episcopacy 

Sts. Barsanuphius and John: On natural and demonic despondency

 Question: "Whence comes despondency? And what should one do when it appears?"

Response: There is a natural despondency that comes from weakness, and there is a despondency that comes from a demon. If you want to test these, do so in the following way. Despondency that comes from the demon appears just before the moment when one requires rest. For when one begins a task, even before completing a third or a quarter of the work, despondency drives one to abandon the task and leave. Therefore, one should not tolerate it, instead praying, remaining seated for the task, and persisting. For when the enemy sees that one is praying for this reason, he ceases; for he does not want to give any opportunity for prayer. Natural despondency arises when one labors beyond one's strength and is obliged to refrain from doing any more. Therefore, natural despondency is caused by bodily weakness. In this case, one should test one's strength and give rest to the body in godly fear.

+Sts. Barsanuphius and John, from Letters, Volume 2, #562

St. Peter of Damascus: That one should not despair

 Even if you are not what you should be, you should not despair. It is bad enough that you have sinned; why in addition do you wrong God by regarding Him in your ignorance to be powerless? Is He, who for your sake created the great universe that you behold, incapable of saving your soul? And if you say that this fact, as well as His incarnation, only makes your condemnation worse, then repent; and He will receive your repentance as He accepted that of the prodigal son (cf Luke 15:20) and the prostitute (cf Luke 7:37-50). But if repentance is too much for you, and you sin out of habit even when you do not want to, show humility like the publican (cf Luke 18:13): this is enough to ensure your salvation. For he who sins without repenting, yet does not despair, must of necessity regard himself as the lowest of creatures, and will not dare to judge or censure anyone. Rather, he will marvel at God's compassion, and will be full of gratitude towards his Benefactor, and so may receive many other blessings as well. Even if he subject to the devil in that he sins, yet from fear of God he disobeys the enemy when the latter tries to make him despair. Because of this he has his portion with God, for he is grateful, gives thanks and is patient, fears God, does not judge so that he may not be judged. All these are crucial qualities. It is as St. John Chrysostom says about Gehenna: it is almost of greater benefit to us than the kingdom of heaven, since because of it many may enter the kingdom of heaven, while few enter for the sake of the kingdom itself; and if they do enter it, it is by virtue of God's compassion. Gehenna pursues us with fear, the kingdom embraces us with love, and through them both we are saved by God's grace.

+St. Peter of Damascus, from The Philokalia, Volume 3

Metropolitan Hierotheos of Nafpaktos: Hannah's Despondency

Hannah [the mother of the prophet Samuel, 1 Kings 1:7] did not want a child in order to satisfy her selfishness, but to dedicate it to God. As St. John Chrysostom again comments, Hannah did not simply long for a child, "but to offer up fruit to God". She did not even want a child to satisfy [her husband] Elkanah and to attract his attention, "but so that she might display some fruit for God". It is obvious here that her purpose was holy. Her aim was the glory of God.
The conclusion for all this is that Hannah's sorrow and grief were not psychologically unhealthy but purely theological. For that reason they were blessed by God, because the intention behind what we do plays and important role and has great significance. If we weep and are distressed on account of our passions, particularly on account of pride and self-centeredness, that is not blessed by God. Not only, is it not blessed, but it has terrible consequences for our psychosomatic constitution. Dealing in an unhealthy way with various problems that arise in our life wears out out body and deadens our soul, because when there is bitterness in us, the All-Holy Spirit cannot act. It is a fact that, when we are embittered for psychological reasons, the Holy Spirit is unable to act and consequently spiritual life cannot develop within us.
+Metropolitan Hierotheos of Nafpaktos, from The Seer: The Life of the Prophet Samuel and its Relevance Today, Chapter 1, God, Hannah and Elkanah. Hannah's despondency.