A wise person knows how to extract the essence of these thoughts…
I received from my teachers and from texts that each day's prayers must have a different mystical intention. Thus, it says in the Talmud: "...if a person is able to say something new." This is because the essence of prayer is to extract the 288 Sparks of the broken vessels, which is the mystery of raising the "feminine waters", to malchut, in order to reunite the wife to her husband. (This refers to the Shechinah with the sefira of tiferet.) This occurs when extraneous thoughts arise in one's mind during prayer. A wise person knows how to extract the essence of these thoughts, which is the holy spark found among the impure shells.
For instance, if a person has lustful thoughts, which come from the side of chesed, as it is written: "If a man takes [has incestuous relations with] his sister, it is a shameful thing (chesed) (Lev. 20:17), he should realize that this pleasure's whole existence derives from the one holy spark within it. [How much greater, then, is the pleasure] of clinging to its root, where it is beyond limit. The same applies if a person has thoughts of idolatry, G‑d forbid, or murder, which is from the left column. However, it is dangerous to expound on this theme, and a wise person will be silent. One needs a truly broad mind and tremendous concentration in order that his mouth and heart be aligned…
Now, we see for ourselves that one day's thoughts can never be like another's - and so too, the prayers one formulates according to these thoughts. But for this, one needs a truly broad mind and tremendous concentration in order that his mouth and heart be aligned. This is not the case of one who prays by rote, each day the same. His mouth routinely utters the words, and his head bows automatically when he reaches "Modim" [the "Thanksgiving" section of the Standing Prayer]. His heart is absent, as Tosephot writes in the name of the Jerusalem Talmud: "We are grateful to the head that bows by itself at Modim." (Rosh Hashanah 16b)
For this reason, it seems to me, there are ten types of prayer, which correspond to the ten qualities of malchut, which is called "prayer" (specifically the last quality of malchut - malchut of malchut). Now, each day of a person's life, he must repair one spark of these ten qualities, until the very end of his life, when he repairs the last quality of malchut and returns in perfect repentance to malchut/prayer - each individual according to his level and his personal channel of influence. This is similar to the generation before the Mashiach, when the entire world will be repaired down to the "heels", and all the sparks of the universal malchut will ascend. Then "death will be swallowed up forever" (Isaiah 25:8), and the Mashiach will come. So too, the life of each individual is a complete structure. If he is concerned with the good of the Shechinah, he is answered immediately…
Thus, a person should thus realize that prayer is not for his own sake, but for the sake a higher purpose - for the good of the Shechinah. The Arizal wrote that if a person prays for himself, the Shechinah laments over him: "G‑d has delivered me into their hands; I am unable to rise" (Lamentations 1:14). But if he is concerned with the good of the Shechinah, he is answered immediately. Thus, it is written in the Tikunei Zohar: "If the Shechinah is there, they immediately open [the supernal gates] for him." (Tikunei Zohar p. 55a. See, also, the end of Tikun 33) Furthermore, his requests are included in bina, which is called the "mother of all living", for all souls are part of the Shechinah, and he too will be answered. However, if he prays for the Shechinah in order to be answered, he creates a barrier. May G‑d enlighten us to serve him in truth and simplicity!
Now, the sign that your prayers have been answered is alluded to in the verse: "You will direct their heart, Your ear will hear" (Psalms 10:17). If [Heaven] helps him so that he can concentrate on his prayers, then certainly "Your ear will hear". For were it not a propitious time for him to enter the King's chamber and be answered, he would be unable to concentrate. But since he has come before the King, his request will certainly be fulfilled, for nothing can keep G‑d from fulfilling his desires and requests, for He is the ultimate love and compassion.
Still, there are those who come before the King and are not answered. This is like a king whose consort has sinned. The king eventually dismisses her, and she travels far away. One day, the king must go to that place on royal affairs. When his consort hears that he is coming, she devises a plan to see him. She comes before him and pleads with him. She tells him how bitter her life has been since she left the king, and she relates to him everything that happened to her since then. Ultimately, the king forgives her and fulfills her requests. However, if she comes before him with threats and accusations, claiming that he betrayed her, her words will go unheard - unless she finds the king in good spirits. Then her words will make an impression on him, and he will realize that her claim that he abandoned her is correct, and that his actions were inappropriate for a king. Then he will fulfill her will, and answer her favorably, despite the fact that she spoke accusingly.
This is called the "Shechinah quarrels with her husband". It is enough of an explanation for one who understands.
[Translation and commentary by Eliezer Shore from "Sefer Baal Shem Tov on the Torah"; Reprinted by permission from wwwbaalshemtov.com]