Every Jew Holds a Portion of Hashem
Explaining the formula said before mitzvos, Rav Tzadok teaches that every Jewish soul is a real share of Hashem, even in exile and even at its lowest.
Rav Tzadok takes up the formula said before mitzvos, 'for the sake of the unification of the Holy One, blessed be He,' whose meaning the Chavos Yair wrote that he could not find, and explains it in a way that reaches much further. Every Jewish soul, he writes, is truly a portion of Hashem above. All these souls flow from one source, called Knesses Yisroel, which is also the Shechinah, the Mother, while Hashem is the Father. That is why the Shechinah goes into exile with Israel and dwells with them even in their impurity. So even the lowest of the low carries a real share of life that Hashem Himself apportioned from above. The mitzvos are how this hidden share grows. Each act, done with the whole of one's mind and strength, joins the portion within to its source, and out of that union a new and deeper understanding is born.
Source: Dover Tzedek, Kuntres Dover Tzedek, Eruvin 1
When you notice yourself writing someone off today, including yourself, pause and say quietly that there is a portion of Hashem inside this person. Before you davven or do a mitzvah, take a breath and have in mind that you are connecting the part of Him inside you to its source. If you are feeling low, choose one small mitzvah, such as a coin for tzedakah or a kind word, and do it with full attention, as a way of letting that hidden portion grow.