Our Gemara mentions the halakhic principle of We Do Not Pass Over a Mitzvah אין מעביריו על המצוות. That is, once we are engaged in one mitzvah or even get in touch with the process, we are not allowed to pass it over and go to another mitzvah.

There is a Beautiful chassidish peshat in this articulated by the Tiferes Shlomo (See Shemini, and Vaeschanan, Shabbos Shuva). The word “to pass over“ in Hebrew מעביר Bears close resemblance to the word sin, or transgression “aveira”. His point is that when one begins a holy act such as to pray or to perform a mitzvah, he should not despair by thinking about his sins, telling himself he is unworthy and that God has no interest in him. Rather, We Do Not Pass Over a Mitzvah אין מעביריו על המצוות, we do not remind ourselves of our sins to stop us and cause us to pass over doing the mitzvah.

He also mentions that one of the functions of pesukei dezimrah The opening psalms of prayer before we get to Shema and Shemoneh Esre is to remove the “shells“ kelipos. In this case he says the ecstasy of praising God and becoming attached to Him helps remove the sense of being stained and unworthy.

Aside from this being a beautiful peshat, we also can see something that I’ve pointed out at other times. The way in which mysticism expresses psychological ideas but in a different language. So the idea that the introductory Psalms remove the kelipos or “shells” is at least understood on one level is getting past psychological inhibitions and despair so that we can rejoice in attachment to God.