My friends, God does not ask or desire that man should mourn from sorrow of heart, but rather that, out of love for Him, he should rejoice with spiritual laughter. Remove the sin, and the tear of sorrow is superfluous for your eyes.

St. John Climacus

In going to church, think that you art going to the house of the King of Heaven, where with fear and joy one ought to stand as in heaven before the King of Heaven. While standing in church, do not look around to the sides and do not look at how someone is standing and praying, lest you be condemned with the Pharisee, since you did not come to judge others, but to ask for mercy for yourself from God the Judge and Knower of hearts. Gaze with compunction toward the altar alone, where the holy sacrifice is offered. More than anything else, beware of laughter and conversations, for whoever laughs or converses while standing in church does not render honor to the holy place and tempts others and prevents others from praying.

St. Tikhon of Zadonsk

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 proud man thinks he can comprehend everything with his mind, but God does not grant this.  But we know the Lord:  He has made Himself manifest to us in the Holy Spirit, and the soul knows and is joyful and at ease, and in this lies our hallowed life.

St. Silouan the Athonite

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

St. Ambrose of Optina

These eight passions should be destroyed as follows: gluttony by self-control; unchastity by desire for God and longing for the blessings held in store; avarice by compassion for the poor; anger by goodwill and love for all men; worldly dejection by spiritual joy; listlessness by patience, perseverance and offering thanks to God; self-esteem by doing good in secret and by praying constantly with a contrite heart; and pride by not judging or despising anyone in the manner of the boastful Pharisee (cf. Luke 18 : 11–12), and by considering oneself the least of all men. When the intellect has been freed in this way from the passions we have described and been raised up to God, it will henceforth live the life of blessedness, receiving the pledge of the Holy Spirit (cf. 2 Cor. 1 : 22). And when it departs this life, dispassionate and full of true knowledge, it will stand before the light of the Holy Trinity and with the divine angels will shine in glory through all eternity.

St John of Damascus