Prayer is the fruit of joy and thankfulness.
Prayer is the remedy for gloom and despondency.
Do not pray that your own will may be done, for your will may not accord with the will of God. But pray as you have been taught, saying: Thy will be done in me. Pray to him in this way about everything – that his will be done. For he desires what is good and profitable for your soul, whereas you do not always ask for this. Often in my prayers I have asked for what I thought was good, and persisted in my petition, stupidly trying to force the will of God, instead of leaving it to him to arrange things as he knows best. But afterwards, on obtaining what I asked for, I was very sorry that I did not pray rather for God’s will to be done; because the thing turned out to be different from what I expected.
What is good, except God? Then let us leave all our concerns to him, and all will be well. If you long for prayer, renounce all to gain all. At the time of trials and temptations, use a brief but intense prayer. When you are in the inner temple, pray not as the Pharisee, but as the publican. Strive never to pray against anyone. If when you are praying no other joy can attract you, then truly you have found prayer.”
(Evagrius of Pontus – d. 399AD, The Time of the Spirit: Readings Through the Christian Year, p 102)