Even a pious person is not immune to spiritual sickness if he does not have a wise guide -- either a living person or a spiritual writer. This sickness is called prelest, or spiritual delusion, imagining oneself to be near to God and to the realm of the divine and supernatural. Even zealous ascetics in monasteries are sometimes subject to this delusion, but of course, laymen who are zealous in external struggles (podvigi) undergo it much more frequently. Surpassing their acquaintances in struggles of prayer and fasting, they imagine that they are seers of divine visions, or at least of dreams inspired by grace. In every event of their lives, they see special intentional directions from God or their guardian angel. And then they start imagining that they are God's elect, and often try to foretell the future. The Holy Fathers armed themselves against nothing so fiercely as against this sickness -- prelest.
Whether you pray with brethren or alone, try to pray not simply as a routine, but with conscious awareness of your prayer. Conscious awareness of prayer is concentration accompanied by reverence, compunction and distress of soul as it confesses its sin with inward sorrow.
St. Peter of Damascus teaches, 'When joy comes, represent sorrow to yourself; and when you are encompassed by sorrow, try to awaken joy.' Thus you will be safeguarded both against deception and against despair.
Join to every breath a sober invocation of the name of Jesus and the thought of death with humility. Both these practices bring great profit to the soul.
Bring before your eyes the blessings, whether physical or spiritual, conferred on you from the beginning of your life down to the present, and call them repeatedly to mind in accordance with the words: 'Forget not all His benefits' (Ps. 102:2). Then your heart will readily be moved to the fear and love of God, so that you repay Him, as far as you can. by your strict life, virtuous conduct, devout conscience, wise speech, true faith and humility - in short, by dedicating your whole self to God. When you are moved by the recollection of all these blessings which you have received through God's loving goodness, your heart will be spontaneously wounded with longing and love through this recollection or, rather, with the help of divine grace.
As for uprooting your passions, begin with self-reproach and with awareness of your own weaknesses; and consider yourself to be deserving of afflictions.
It is not always possible to fulfill the usual rules; one must take circumstances into account and try to fulfill what they make possible, as far as one can. The demons themselves are not unmindful of this law. So, being in constant enmity with us, they prevent us from doing what is possible and urge us to do what is impossible.
The grace of the Spirit is one and unchanging, but energizes in each one of us as He wills. When rain falls upon the earth, it gives life to the quality inherent in each plant: sweetness in the sweet, astringency in the astringent; similarly, when grace falls upon the hearts of the faithful, it gives to each the energies appropriate to the different virtues without itself changing.