Tedium is the granddaughter of despondency, and the daughter of slothfulness. In order to drive it away, labor at your work, and do not be slothful in prayer. The tedium will pass, and zeal will come. And if to this you add patience and humility, then you will be rid of all misfortunes and evils.
Some people when praised for their virtue are delighted, and attribute this pleasurable feeling of self-esteem to grace. Others when reproved for their sins are pained, and they mistake this beneficial pain for the action of sin.
You write that after Communion you felt well. Glory be to God, Who comforts our unworthiness. And as regards the fact that this soon passed, here also is seen His fatherly providence for us. For continual consolation enfeebles the soul and makes it slothful, or leads to even greater harm. That is why the Lord takes it away quickly and again makes us feel our weakness, our helplessness, and our sinfulness. We must humble ourselves more, reproach ourselves, offer repentance for our sins, and not desire consolations, but patiently endure what God allows. Dryness and cooling of fervor are also permitted on account of vainglory.
Often when someone throws a rock at a dog, rather than rushing at the person who threw the stone, the dog will run and bite the stone. We do the same thing. The tempter uses someone else to tempt us, either in word or deed, and, rather than deal with the tempter who threw the stone, we bite the rock, our fellow man that the hater of the good used against us.
I must tell you that annoying incidents are unavoidable in this life. Those who are experienced in the spiritual life say that such incidents can even bring profit to the soul. Through annoying incidents we come to recognize that we are impatient - and if we are impatient, that means we are proud. And this awareness should dispose us to self-reproach and repentance, and to asking mercy from the Lord in prayer. But without annoying incidents a man is inclined to conceit.
This prayer should never be absent from you: 'Lord Jesus Christ, Son and Logos of the living God, through the Theotokos and all the Saints, have mercy upon me, Thy sinful and unworthy servant.' (This is the actual Jesus Prayer: 'O LORD JESUS CHRIST, SON OF GOD, HAVE MERCY UPON ME, A SINNER.') Always say this prayer both with your mouth and with your mind, day and night, wherever you may be, whether eating, walking, working, or sitting. Always meditate on it, as it benefits you a great deal, frees you here from every evil, delivers you there from eternal Hell, and renders you worthy of going to Paradise, our heavenly country.