Some say: what is the use of a great fast, when this fast weakens a person to such an extent that he cannot even pray with attention, especially stand in church and listen to reading and singing? Don't listen, Christians, to people who say that. If you listen to them, then you need to leave all the fasts - both great and small. Fasting weakens the body of a person, but this weakening is also salvific for a person, for with this weakening, passions weaken in us - the main enemies of our salvation, and with this weakening, the power of God is instilled in us, by which alone we are saved.
Yes, the power of God is made perfect in weakness. Then the work of salvation is accomplished in us, when we begin to realize that we can do nothing for our salvation. Fasting weakens the strength of a person, but why should a fasting person be afraid? The demons do not dare to approach the fasting one, the guardian angels of our life relentlessly visit those who exhaust their bodies with fasting.
Therefore, do not be discouraged when fasting weakens you somewhat and brings you to exhaustion; if you fast out of obedience to the Holy Church, to please God and save your soul, then no matter how weakened you are from fasting, your fasting will certainly be pleasing to God and saving for you. And the Angels, who at every church record those who fast, will also include you in their list.
Why be discouraged when you fast? God is with you, guardian angels are with you, the prayers of the Holy Church are for you. Amen.