This is what a person should take to heart:
He should consider how his soul descended to such a low level, and this should make his heart very bitter, and he should cry out to Hashem in his pain, as it is written (Eicha 2:18): “their hearts cried out to Hashem,” until he “goes out of his mind,” meaning, he goes out his previous state of mind that he was connected to all day, and he will firmly bind his thoughts to this deep bitterness of his soul, until he removes his entire mental capacity from dwelling on his physical matters.
This bitterness is called “wine that intoxicates,” and when he “drinks” this, he will forget his spiritual poverty.
This bitterness over his spiritual state has the power to take the person out of his material concerns, so that he can truly focus, with all his mental capacity, on only connecting to Hashem. This is the “river of fire” that the person makes for himself. By “immersing” himself in this “river” of bitterness, he can spiritually cleanse himself so that he can spiritually ascend to connect to Hashem.
Through this, he can [afterwards] pray to Hashem, and say directly to Hashem Himself, from the depths of his heart “may You, Hashem, be “blessed/drawn down and revealed.”
The word “blessed” can also mean drawn down, like a “בריכה-pool of drawn water” that flowed down from a higher place. Thus, when we say "הָּּתַא ךּורָּּב", it is not only a praise of Hashem, but also a request that Hashem should become drawn down and revealed. This request is most meaningful to one who is bitter over the fact that in his life Hashem’s Presence is not drawn down and revealed.
Because this bitterness is regarding his past, since he is bitter over the concealment of Hashem’s Presence in his life. Since, if he would perceive Hashem’s presence at least as strongly as he perceives the presence of physical people, then he would never sin, like Rabbi Yochanan ben Zakai told his students (Brachos 28b): “I wish you would at least have the fear of Heaven [as much as you fear physical people, since a person doesn’t sin when he knows other people are watching him.]”
Therefore, we he returns to Hashem, he will ask Hashem from the depths of his heart to give him the ability to perceive His Presence. This is what we are ask when we say “הָּ ת א ך ורָּ ב”, may You, Hashem, be “drawn down and revealed,” and all of the prayers and requests in the daily order of prayers are set up regarding this essential request- that we should perceive Hashem’s Presence.
Similarly, this will bitterness will inspire the person to truly accept Hashem’s Kingship when he recites Shema, since, in truth, his inner desire is to connect to Hashem, and his soul is bitter from his distance from “the Light of the Countenance of the King” (see Mishlei 16:15 and Rashi there).
Even though in truth he is still far from Hashem, despite his bitterness, nonetheless, there is still a difference between the one who is far from perceiving Hashem and unconcerned about it, and the one who is far from perceiving Hashem and it bothers him, since the fact that it bothers him is already a certain connection to Hashem, as is explained elsewhere.
Regarding this “wine” of bitterness the person also, the person needs to first “squeeze” himself, as it were, meaning, to consider himself like leftovers that no one needs, i.e., he needs to squeeze out his ego that makes him think that the world revolves around him. How does he squeeze out his ego? By thinking deeply into all his thoughts, words, and actions, that he performed in his life that were not for the sake of Hashem, so that he will be very humble. Realizing his own compromised spiritual status, he will have no reason to think he is better than anyone else. This process is discussed at length in Tanya chapter 29 and 30.
