In no art do the artists judge the result of their work by the tools they use, but they await the work's completion and by it judge the art. Adopting such a practice with regard to food, not placing all your hope on fasting, but fasting moderately and according to the amount of your strength, strive toward mental activity. In this way you can avoid pride and will not spurn God's good works, sending up praises to God for everything.
You ask for some way of completely eradicating irritability. The inclination to irritability is given us to use against sin, and we were never meant to use it against our fellow men. When we do, we act contrary to our true nature.
Forgive and pray, in order to live your life serenely. And do not do to others that which you do not want them to do to you, or return the evil which they have done to you.
Think also of this: the person who is bound to earthly things may rejoice but may also be upset or disturbed or grieved over earthly things: his mind is exposed to continual changes. But the joy of your master (Matthew 25:21) is enduring, for God is unchangeable. Thus control your tongue at the same time as you discipline your body with fasting and strictness. Talkativeness is a great enemy of prayer. A spate of fluttering words stands in the way of the words of prayer. This is the reason that we shall render account for every careless word we utter (Matthew 12:36). One does not bring the dust of the road into a room that one wishes to keep clean; thus keep your heart free from gossip and chatter about the events of the day that is past.
The holy Fathers' counsel is to begin with small things, for, says Ephraim the Syrian, how can you put out a great fire before you have learned to quench a small one? If you wish to set yourself free from a great suffering, crush the small desires, say the holy Fathers. Do not suppose that the one can be separated from the others: they all hang together like a long chain or a net.
Faith is truly a gift, gained for us through Christ's advent. But this does not abolish our freedom or responsibility. God desires of us not only faith but action too.
Do not say...that one or two books is sufficient for instructing the soul. After all, even the bee collects honey not from one or two flowers only, but from many. Thus also he who reads the books of the Holy Fathers is instructed by one in faith or in right thinking, by another in silence and prayer, by another in obedience and humility and patience, by another in self-reproach and in love for God and neighbor; and, to speak briefly, from many books of the Holy Fathers a man is instructed in life according to the Gospel.
Cultivate patience. Patience is a heavenly gift, a gift from the Heavenly Father... With patience, and love for your fellow men, you become a victor in life's continual trials.
Condemn only yourself, and you will not be condemned at His second and awful coming. From your whole heart remit the sins of whoever sins before you, and your Father who is in heaven will remit your sins.
Remember always that, once we have decided consciously to strive after righteousness, we cannot escape catastrophes and sorrows, no matter where we are.