The most important thing during illness is to offer to God patience and thanksgiving for His merciful visitations. Sickness purifies sins and gives one time to meditate on the past.
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.
People have to answer greatly for not keeping the rules of the Church with respect to the fasts. People justify themselves by saying that they never considered it a sin to eat dairy products during the fasts. They repent and consider themselves sinners in every other respect, but they do not think to repent about not keeping the fasts. Meanwhile, they are transgressing the commandment of our holy Mother, the Church, and according to the teaching of the Apostle Paul, they are as the heathen and publicans because of their disobedience.
A man may seem to be silent, but if his heart is condemning others, he is babbling ceaselessly. But there may be another who talks from morning till night and yet he is truly silent, that is, he says nothing that is not profitable.
Most people desire and seek after prosperity in this life, and they strive to avoid sorrows. While that seems very good and pleasant, constant prosperity and good fortune do a person harm. He falls into a variety of passions and sins, and angers the Lord, while those who live a life of sorrow come closer to the Lord and more readily attain unto salvation, for the Lord called the life of happiness the broad path. The wide gates and the broad way lead to destruction, and many there be who take that way (Matthew 7:13). It is the narrow way and the strait gate which lead to life eternal, and few there be who find it (Matthew 7:14). Thus, according to His love for us, seeing the possible benefit [of sorrows] to those who are worthy, the Lord moves many off the broad road and puts them on the narrow, sorrowful path, so that in [their] patient endurance of sickness and sorrow, He might effect their salvation and grant them life eternal.
Keep your conscience keen and bright, and refrain from hankering after, or expecting, consolation. Leave that to God. He knows when, where, and how to give it to you.
Wherever we are and whatever our circumstances, the enemy always tries to prevent us from actively responding to the call. Pray for help. For help that you may never fail to respond. And beware lest, having received help and having done the right deed because of it, you should grow proud and acquire the habit of condemning others, in the secret chambers of your heart. Beware! For this would make all the fruits of your good works wither.
Remember always that, once we have decided consciously to strive after righteousness, we cannot escape catastrophes and sorrows, no matter where we are.
The best medicine for pride, man’s greatest sickness of soul, is humility. Words cannot describe or explain it, but the Fathers say that he who strives hard to live according to the precepts of our Lord, and is fully aware of his own sins, acquires it steadily. Therefore be very careful never to think yourself good, or the least bit better than others.
When God, using our conscience, calls us to righteousness and yet our self-will opposes Him, He respects our freedom and lets our own will be done; but then, alas, our minds grow dull, our will slack, and we commit iniquities without number. On the other hand, the fruits of the spirit are soon granted to them who follow the commandments of Christ our Lord.