One who is engaged in the spiritual struggle must have at every moment the following four things: humility, extreme attentiveness, refutation (of the thoughts) and prayer.
Humility, in so far as its adversaries in combat are the demons of pride, so that he will have at hand Christ's help in his heart, for ' the Lord resists the proud.' (James 4:6; 1Peter 5:5)
Attentiveness, so that one does not allow the heart to have any thought, no matter how good it seems.
Denial, so that as soon as one has detected a thought that has come, he may repulse it immediately with anger.
Prayer, so that after refuting a thought, one may immediately cry out to Christ with 'groanings which cannot be uttered' (Romans 8:26) Then the ascetic will see the enemy bound or chased by the honorable name of Jesus, like dust by the wind, or like smoke that vanishes with it's dreams.Saint Hesychius adds the following on the importance of prayer,
One who does not have prayer that is free from the thoughts is without a weapon for battle. I understand prayer to be that which is carried unceasingly within the depths of the soul, so that the enemy who is secretly fighting may be vanquished and scorched by this invocation to Christ. For you must look with the sharply focused eye of the mind so that you will recognize what has entered into it, and after doing so, immediately cut off the head of the snake through refutation, and at the same time call on Christ with groaning. Through experience you will come to know God's invisible help; then you will see clearly the true condition of the heart.
Saint Theophan advises in his commentary on the teaching of Saint Hesychius,
A person whose decision to belong to the Lord is sincere cannot by-pass the path described.Ato the path so that you do not wander all over the place. Be more diligent in your undertaking, and you will find success. However, you must labor with all your might, because without labor there will be nothing.
Reference: The Spiritual LIfe, pp 249-253