They say that Abba Macarius the Egyptian [St. Macarius the Great] on one occasion went up from Scete to the Nitrian mountain, and as he drew near to a certain place, he said to his disciple, "Pass on a little in front of me"; and when he had done so there met him a certain heathen priest, who was running along and carrying some wood about the time of noon. And that brother cried out to him and said, "O minister to devils, where run thou?"  And the priest turned round and smote him with many severe blows, and he left him with but very little breath remaining in him, and he took up his wood and went on his way; and when he had gone on a little further the blessed Macarius met him on his journey, and said to him, "May you be helped, O man of labours?"  And the priest was astonished, and came to him and said, "What fair thing have you seen in me that you should salute me [in this gracious fashion] ?"  And the old man said to him, "I see that you toil, and that you do not know that you are toiling for naught"; then he said to the old man, "At your salutation I also was very sorry, and I learned that you did belong to the Great God. But a wicked monk met me just before you didst, and he cursed me, and I smote him even to death."  And the old man knew that it was his disciple [of whom he spake], and the priest laid hold upon the feet of Macarius, and said to him, "I will not let you [go] until you make me a monk"; and they came to the place where the brother was lying, and they carried him and brought him to the church of the mountain. Now when the fathers saw the heathen priest with him, they marvelled that he had been converted from the error which he had held; and Macarius took him and made him a monk, and through him many of the heathen became Christians. And Abba Macarius said, " ' An evil word makes wicked even those who are good, and a good word makes good even those who are wicked,' as it is written."

from Sayings of the Holy Desert Fathers

O Lord and Creator of all, and especially of Your creature, man: You are the God and Father and ruler of Your children; You are the Lord of life and death; You are the guardian and benefactor of our souls.  You fashion and transform all things in their due season through Your creating Word, as You know to be best in Your deep wisdom and providence.  Receive now those who have gone ahead of us in our journey from this life.  Receive us too at the proper time, when You have guided us in our bodily life as long as may be for our profit.  Receive us prepared indeed by fear of You, but not troubled, not shrinking back on that day of death or uprooted by force like those who are lovers of the world and the flesh.  Instead, may we set out eagerly for that everlasting and blessed life which is in Christ Jesus our Lord, to whom be glory forever and ever.  Amen.

St. Gregory the Theologian

In order that you may move your will more easily to this one desire, in everything—to please God and to work for His glory alone—remind yourself often that He has granted you many favors in the past and has shown you His love. He has created you out of nothing in His own likeness and image, and has made all other creatures your servants; He has delivered you from your slavery to the devil, sending down, not one of the angels, but His Only-begotten Son to redeem you, not at the price of corruptible gold and silver, but by His priceless blood and His most painful and degrading death. Having done all this He protects you, every hour and every moment, from your enemies; He fights your battles by His divine grace; in His immaculate Mysteries He prepares the Body and Blood of His beloved Son for your food and protection. All this is a sign of God’s great favor and love for you; a favor so great that it is inconceivable how the great Lord of hosts could grant such favors to our nothingness and worthlessness.

St. Nicodemus of life Holy Mountain

Where are You pasturing Your flock, O Good Shepherd, who carry the whole flock on Your shoulders? For the whole of human nature is one sheep, and You have lifted it upon Your shoulders. 

Show me the place of peace, lead me to the good pasture that will nourish me, call me by name so that I, Your sheep, may hear Your voice, and by Your speech give me eternal life. Answer me, You whom my soul loves. 

I give You the name “You whom my soul loves” because Your name is above every name and above all understanding, and there is no rational nature that can utter it or comprehend it. Therefore Your name, by which Your goodness is known, is simply the love my soul has for You. How could I not love You, when You loved me so much, even though my heart was black, that You laid down Your life for the sheep of Your flock? A greater love cannot be imagined than exchanging Your life for my salvation. 

Show me then (says my soul) where You pasture Your flock, so that I can find that saving pasture too, and fill myself with the food of heaven without which no one can come to eternal life, and run to the spring and fill myself with the drink of God. You give it, as from a spring, to those who thirst—water pouring from Your side cut open by the lance, water that, to whoever drinks it, is a fountain of water springing up to eternal life. 

If You lead me to pasture here, You will make me lie down at noon, sleeping at peace and taking my rest in light unstained by any shade. For the noon has no shade and the sun stands far above the mountain peaks. You bring Your flock to lie in this light when You bring Your children to rest with You in Your bed. But no one can be judged worthy of this noonday rest who is not a child of light and a child of the day. Whoever has separated himself equally from the shadows of evening and morning, from where evil begins and evil ends, at noon he will lie down and the sun of righteousness will shine on him. 

Show me, then (says my soul), how I should sleep and how I should graze, and where the path is to my noonday rest. Do not let me fall away from Your flock because of ignorance and find myself one of a flock of sheep that are not Yours. 

Thus spoke my soul, when she was anxious about the beauty that God’s care had given her and wanted to know how she could keep this good fortune forever.

St. Gregory of Nyssa

Grumbling is caused by misery and it can be put aside by doxology (giving praise). Grumbling begets grumbling and doxology begets doxology. when someone doesn’t grumble over a problem troubling him, but rather praises God, then the devil gets frustrated and goes off to someone else who grumbles, in order to cause everything to go even worse for him. You see, the more one grumbles, the more one falls into ruin. 

Sometimes the devil deceives us and makes us unable to be pleased with anything; however, one can celebrate all things in a spiritual manner, with doxology, and secure God’s constant blessing.

St. Paisios of Mount Athos

Thanksgiving dulls the fierceness of your illness!  Thanksgiving brings the ailing person consolation!  The tutored heart, sweetened by thanksgiving, is renewed through the power of a living faith.  Illumined by the sudden light of faith, the mind begins to contemplate the divine Providence of God... The sickbed is often the place where one gains the knowledge of God and the knowledge of self.  The suffering of the body often brings spiritual joys, and the sickbed is often watered with tears of repentance and tears of joy in God.

St. Ignatius Brianchaninov

The apostle notes four types of prayer. "My advice is that first of all supplication should be offered up for everyone, prayers, pleas, and thanksgiving" (I Tim. 2:1)… A supplication is a plea or petition made on account of present and past sin by someone who is moved by contrition to seek pardon. In prayers we offer or promise something to God. The Greek term means "vow"… Third comes pleas. We usually make them for others when we ourselves are deeply moved in spirit. We offer them for those dear to us or when we beg for peace in the world… Fourth are thanksgivings. Unspeakably moved by the memory of God’s past kindnesses, by the vision of what He now grants or by all that He holds out as a future reward to those who love Him, the mind gives thanks. In this perspective richer prayers are often uttered. Looking with purest gaze at the rewards promised to the saints, our spirit is moved by measureless joy to pour out wordless thanksgiving to God.

St. John Cassian

We must begin with thanksgiving for everything. The beginning of joy is to be content with your situation.

St. Ambrose of Optina

He who shall preserve the life bestowed upon him, and give thanks to Him Who imparted it, shall receive also length of days forever and ever. But he who shall reject it, and prove himself ungrateful to his Maker, inasmuch as he has been created, and has not recognized Him Who bestowed the gift upon him, deprives himself of the privilege of continuance forever and ever. And, for this reason, the Lord declared to those who showed themselves ungrateful towards Him: ‘If you have not been faithful in that which is little, who will give you that which is great?’ (cf. Lk. 16:11) indicating that those who, in this brief temporal life, have shown themselves ungrateful to Him Who bestowed it, shall justly not receive from Him length of days forever and ever.

St Irenaeus of Lyon

The mouth which is continuously giving thanks receives blessing from God. In the heart that always shows gratitude, grace abides.

St Isaac of Syria