Everyone must know that the essence of Divine service is to serve HaShem in truth. At every moment, examine and investigate all of one’s actions, even the good things and mitzvot that one does. If one finds in them (G-d forbid) any mixture of intent, pointing in any other direction (G-d forbid), or whether it be enjoyable, to the honor of oneself; we see that (such a one’s) intent of Divine service is not for the sake of HaShem’s holy, honorable, and awesome Name. All such a one’s actions are not for the sake of HaShem alone, in truth, and with a pure heart.
Devekut-Bonding with G-d: The Ba’al Shem Tov’s Insights into Receiving the Spirit of Prophecy, by Ariel Bar Tzadok
If you can pray well, even once, you can uplift all the lost prayers, those prayed without emuna and cleaving to Hashem, that were previously left below. Together, all your prayers will be perfected and rise to the realm of Supernal Desire.
– Tiferes Shlomo, Shabbat Teshuva
From Heart of Prayer: Baal Shem Tov, by Tzvi Meir Cohn
The primary way to advance to new levels of understanding is to study Torah and pray with all of your strength. Then, you attach yourself to Hashem, may He be blessed, that dwells within the letters of Torah and prayer. This infusion of Divine light subdues any physical inclination, and you can experience the abnegation or divestiture of your physical being. Then, you will enter the Supernal worlds and constantly rise to new levels of understanding and clarity.
Toldos Aharon, Shelach
Heart of Prayer: Baal Shem Tov, by Tvi Meir Cohn