The most important thing in any good effort and the height of all activities is to persevere in prayer, by means of which we can always acquire through supplication the other virtues from God as well.
When you are praying alone, and your spirit is dejected, and you are wearied and oppressed by your loneliness, remember then, as always, that God the Trinity looks upon you with eyes brighter than the sun; also all the angels, your own Guardian Angel, and all the Saints of God. Truly they do; for they are all one in God, and where God is, there are they also. Where the sun is, thither also are directed all its rays. Try to understand what this means.
Unless the inner man meditates upon the law of God and is nourished thereby, unless he is strengthened by reading and by prayer, he is conquered by the outer man, and he serves his master.
The head of every good striving and the pinnacle of all corrections is to persevere in prayer, by which we may ever obtain, through entreaty of God, all the other virtues as well. By prayer those who are worthy partake of the sanctity of God and spiritual activity and the union of the mind with the Lord in unutterable love. He who constantly forces himself to endure in prayer is roused by spiritual love to Divine fervor and flaming desire towards God, and he receives, according to his measure, the grace of spiritual, sanctifying perfection.
Pray simply. Do not expect to find in your heart any remarkable gift of prayer. Consider yourself unworthy of it. Then you will find peace. Use the empty cold dryness of your prayer as food for your humility. Repeat constantly: I am not worthy; Lord, I am not worthy! But say it calmly; without agitation.
In everything we do, God looks as the aim, whether it is for Him or for some other purpose we act. So, when we wish to do something good, let us have as our aim not to please men but to please God, so as to have our eyes always fixed on Him, doing everything for Him, lest we bear the labor but lose the reward.
Prayer is truly a heavenly armor, and it alone can keep safe those who have dedicated themselves to God. Prayer is the common medicine for purifying ourselves from the passions, for hindering sin and curing our faults. Prayer is an inexhaustible treasure, an unruffled harbor, the foundation of serenity, the root and mother of myriads of blessings.
Do not be always wanting everything to turn out as you think it should, but rather as God pleases; then you will be undisturbed and thankful in your prayer.