As the hermit Nikephoros said in V. Sventsitsky's book "Citizens of Heaven":

"The Lord demands not hunger, but podvig. Podvig is what a person can do the greatest in his power, and the rest is by grace. Our strength is now weak, and the Lord does not demand great feats from us.

I have tried to fast a lot, and I see that I can't. I am exhausted - I have no strength to pray properly. Once I was so weak from fasting, I can't get up to read the rule."

Here is an example of improper fasting.

Ep. Herman writes: "Exhaustion is a sign of the impropriety of fasting; it is as harmful as satiety. And the great elders ate soup with butter on the first week of Great Lent. Sick flesh should not be crucified, but must be supported."

Thus, any weakening of health and ability to work during fasting already speaks of its irregularity and exceeding its norm.

"I prefer that they should be exhausted more from work than from fasting," one pastor said to his spiritual children.

It is best when fasting people are guided by the instructions of experienced spiritual leaders. It is worth remembering the following incident from the life of St. Pachomius the Great. In one of his monasteries, a monk was in the hospital, exhausted by illness. He asked the servants to give him meat. They refused his request, based on the rules of the monastery rule. The sick man asked to be attributed to Fr. Pachomius. The monk was struck by the extreme exhaustion of the monk, he wept, looking at the sick man, and began to reproach the hospital brethren for their hardness of heart. He gave orders to immediately fulfill the request of the sick man, in order to strengthen his weakened body and cheer up his despondent soul.

The wise ascetic of piety, Abbess Arsenia, wrote to the elderly and sick brother of Bishop Ignatius (Brianchaninov) during the days of Great Lent: "I am afraid that you are burdening yourselves with heavy lenten food, and I ask you to forget that it is now fasting, and to eat non-nutritious food, nutritious and light. The difference of days has been given to us by the Church as a bridle of healthy flesh, but you have been given the sickness and infirmity of old age." (Indeed, it is difficult for elderly people to change their habitual diet for fasting. Such a change often brings with it stomach diseases and a loss of ability to work to some extent.

However, those who break the fast due to illness or other infirmity should still remember that there may be a certain amount of lack of faith and intemperance.

Therefore, when the spiritual children of Elder Fr. Alexis Zosimovsky had to break the fast on the doctor's prescription, the Elder ordered them to repent themselves in such cases and pray thus: "Lord, forgive me that I broke the holy fast by the doctor's prescription, because of my infirmity," and not to think that this is as if it were necessary.

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Speaking of fasting as a scarcity and a change in the composition of food, it should be noted that this podvig is not counted by the Lord as anything, if a Christian does not at the same time observe the Lord's commandments about love, mercy, selfless service to one's neighbor – in a word, everything that will be asked of him on the day of the Last Judgment (Matt. 25:31-46).

This is already stated with exhaustive clarity in the book of the prophet Isaiah. The Jews cry out to God: "Why do we fast, and you do not see? We humble our souls, but Thou knowest not?" The Lord answered them through the mouth of the prophet: "Behold, on the day of your fasting ye do your will and demand hard labor from others. Behold, you fast for strife and strife, and to strike others with a bold hand; you do not fast at this time so that your voice is heard at a height.