We must always pray to the Lord to tell us what to do, and the Lord will not let us go astray. Adam was not wise enough to ask the Lord about the fruit which Eve gave him, and so he lost paradise. David did not ask the Lord whether it would be a good thing if he took Beth-sheba to wife, and so he fell into the sins of murder and adultery. So with all the saints who sinned: they sinned because they had not called upon God to enlighten and help them. St. Seraphim of Sarov said, ‘When I spoke of myself I was often in error.’
When you are praying, don’t rack your brains to find words. On many occasions the simple, monotonous stammering of children has satisfied their Father who is in heaven. Don’t bother to be loquacious lest the mind is bewildered in the search for words. The tax-collector gained the Lord’s forgiveness with a single sentence, and a single word charged with faith was the salvation of the robber. Loquacity in prayer often fills the head with foolish fancies and provokes distractions. Brevity on the other hand - sometimes only one word is enough - in general favors recollection.
Our prayer reflects our attitude towards God. He who is careless of salvation has a different attitude toward God from him who has abandoned sin and is zealous for virtue but has not yet entered within himself and works for the Lord only outwardly. Finally, he who has entered within and carries the Lord within himself, standing before Him, has yet another attitude. The first man is negligent in prayer, just as he is negligent in life, and he prays in church and at home merely according to the established custom, without attention or feeling. The second man reads many prayers and goes often to church, trying at the same time to keep his attention from wandering and to experience feelings in accordance with the prayers which are read, although he is seldom successful. The third man, wholly concentrated within, stands with his mind before God, and prays to Him in his heart without distraction, without long verbal prayers, even when standing for a long time at prayer in his home or in church.... Every prayer must come from the heart and any other prayer is no prayer at all. Prayer-book prayers, your own prayers and very short prayers, all must issue forth from the heart to God, seen before you.
The enemy of our salvation especially strives to draw our heart and mind away from God when we are about to serve Him, and endeavours to adulterously attach our heart to something irrelevant. Be always, every moment, with God, especially when you pray to Him. If you are inconstant, you will fall away from life, and will cast yourself into sorrow and straitness.
You describe how bitterly you regret the inefficacy of your prayers. Beware: to wish for consolation or revelation in prayer is a sure sign of pride. Pray humbly, in perfect simplicity, seeking salvation only through forgiveness, & having faith that God will extend to you His mercy - as He did to the publican.
To pray with self-constraint is in our power, whereas to pray with compunction depends upon God. We must pray with what prayer we can, and for our self-constraint God will give us compunction also in due time, when this is pleasing to Him.
Prayer demands that the mind should be pure of all thought and should admit nothing not belonging to prayer, even if it were good in itself. As if inspired by God the mind should withdraw from all things and hold its converse with Him alone.