No Christian believing rightly in God should ever be off his guard. He should always be on the look-out for temptation, so that when it comes he will not be surprised or disturbed, but will gladly endure the toil and affliction it causes, and so will understand what he is saying when he chants with the prophet: 'Prove me, O Lord, and try me' (Ps. 26:2 LXX). For the prophet did not say, 'Thy correction has destroyed me,' but, 'it has upheld me to the end' (Ps. 18:35 LXX).
What guarantees a safe journey to eternity is effort, dignity, the sense of being unworthy before God, hope (the spiritual oxygen), consolation, and certainty. Not misery and compelled obedience and forced prayer; not tears and sadness - these all come from Satan. Yes, I ought to weep for my sins, but all the while hoping in God's love. But I cannot stand it if I cry because the devil wants me (to despair). Many times Satan crushes a person with despair and the devil becomes the victor. But this does not happen when one is like a child on his father's arm - trusting. Our trust in God is a ceaseless prayer that brings positive results. Despair comes from the devil. Don't say, 'Oh, what has happened to me?' but give yourself to God totally and hope in Him.
Do not neglect the practice of the virtues; if you do, your spiritual knowledge will decrease, and when famine occurs you will go down into Egypt (Genesis 41:57, 46:6).
We should not miss any chance to us to say the Jesus Prayer. We must not let our mind wander in vain things. In saying the Jesus Prayer one's mind finds rest and joy. It is like small children who for the whole day run around, shouting and playing and hitting each other. But the one thing that gives them rest and great joy is when at night they find themselves in their mother's arms. This way also one's mind instead of being scattered about, out to be devoted to mental prayer.
One time St. Nicodemos, on a feast day, was walking toward the Great Lavra (on Mt Athos). On his way he came across a kellion where he spent the night. At midnight he saw an elder and his accompanying monks entering the church. He secretly went in also, and there he saw the elder and his subordinate monks uttering the Jesus Prayer ('Lord Jesus Christ, Son of God, have mercy on me'), sometimes in a kneeling position, sometimes standing up. And at the time of the Holy Communion, he saw all their faces shining only a little less dimly than the sun.
Observe your thoughts, and beware of what you have in your heart and your spirit, knowing that the demons put ideas into you so as to corrupt your soul by making it think of that which is not right, in order to turn your spirit from the consideration of your sins and of God.