Pray sincerely and slowly…

But for those who have not attained the capability of praying sincerely it is necessary to pray slowly, waiting for a corresponding echo in the heart to each word of the prayer. And this is not always soon given to men unaccustomed to prayerful contemplation. Therefore, for such men, it must be laid down as an absolute rule to pronounce the words of the prayer slowly, and with pauses. Wait until every word gives back its corresponding echo in your heart.
–Saint John of Kronstadt (1829-1908)

Act wisely in prayer…

Do not be foolish in the requests you make to God, otherwise you will insult God through your ignorance. Act wisely in prayer, so that you may become worthy of glorious things. Ask for things that are honorable from Him Who will not hold back, so that you may receive honor from Him as a result of the wise choice your free will had made. Solomon asked for wisdom (3 Kg 3:8-14) – and along with it he also received the earthly kingdom, for he knew how to ask wisely of the heavenly King, that is, for things that are important.
–Saint Isaac of Syria (Seventh Century)

Dryness or difficulty…

Never leave prayer because of dryness or difficulty. Remain before God entirely plunged in His holy love, detached from all desire for your own pleasure. It might help to send out little darts of love, such as, `O my God, my true Good, I am yours!’ and then remain in peace.
–Saint Paul of the Cross (1694-1775)