Saint Hesychius give this advice on our struggle to overcome the passions: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. He may preform great labors and get around things in various ways, but until he comes upon this path, it is to no purpose. I am pointing you directly to 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
For his invisible warfare or conflict with man, especially by means of sinful thoughts and imaginations, the fallen angel relies on the mutual affinity of the sins one with another. This conflict never ceases day or night, but it becomes specially intense and furious when we stand for prayer. Then, according to the expression of the holy Fathers, the devil gathers the most monstrous thoughts from everywhere and pours them on our soul. First he reminds us of all who have wronged or offended us. He tries to present all the insults, wrongs and injuries inflicted on us in the most lurid colors. He points out the necessity for retaliation and resistance to them by demanding justice, common sense, the public good, self-preservation, self-defense. It is obvious that the enemy tries to shake the very foundation of prayer, namely forgiveness and meekness, so that the building erected on this foundation may collapse of its own accord. And this is just what happens, because a person who is full of resentment and who does not forgive his neighbor’s sins is quite unable to obtain compunction or concentrate when he prays. Angry thoughts dissipate prayer; they blow it aside, just as a violent wind scatters seeds thrown by a sower on his field; so the field of the heart remains unsown, and all the ascetic’s hard work comes to nothing.
It is a well-known fact that forgiveness of wrongs and offenses, changing condemnation of our neighbors into kindness and mercy so that we excuse them and blame ourselves, provides the only solid basis for successful prayer. …We must follow our Lord’s example and teaching; we must reject thoughts of earthly glory, success, and earthly plenty; we must refuse joy brought by those fancies and reflections which destroy in us contrition of spirit, concentration and attention during prayer, and which lead to self-opinion and distraction. If we consent to thoughts of resentment and condemnation, thoughts and fantasies of vainglory, pride, love of money and love of the world, and if we do not reject them, but dawdle in them and take pleasure in them, then we enter into fellowship with Satan, and the power of God which protects us will leave us. The enemy then rushes at us with two most grievous conflicts: the conflict with thoughts and fantasies, and the conflict with despondency or sloth. Defeated in the first conflict and deprived of God’s protection, we cannot stand against the second conflict either. This means, the Fathers tell us, that God allows Satan to defeat us until we humble ourselves…
St. Ignatius Brianchaninov: “The Arena”
