At times, in the middle of a weekly fast, the evil inclination may try to overpower you by making you feel the great difficulty of your abstention, telling you that you cannot bear it. At such times, understand in your mind that the evil inclination zealously attempts to obstruct you from attaining a spiritual level, and this is why he harangues you so much.

If you are wise and overpower your evil inclination, at that moment you cause great things Above, as stated in Zohar,¹²⁸ “The Name of the Holy One, blessed is He, is sanctified and elevated when the side of evil (Sitra Achara) is broken and subjugated through a person’s toil in the service of HaShem.” The evil inclination therefore greatly desires to obstruct you from your abstention. However, if you overpower him, the side of evil (Sitra Achara) becomes extremely subdued.

footnotes: ¹²⁸ Zohar Vol. 2, 68a.