Musar su Salmi 119:140

This is what king David, peace be unto him, said: "Whom have I in Heaven [but you]? And having You I desire none on earth" (Tehilim 73:25), and likewise "your Word is very pure; therefore your servant loves it" (Tehilim 119:140). For in truth, the true divine service must be purified far more than gold and silver. This is what was said regarding the Torah: "the Words of G-d are pure words, like silver refined in a furnace on the earth, purified seven times" (Tehilim 12:7).

But those who love G-d, who desire in His service, will rejoice in demonstrating their faithfulness of love before Him, blessed be He, and in strengthening themselves in refining and purifying it. This is what David himself concluded saying "[Your Word is very pure;] therefore Your servant loves it" (Tehilim 119:140).

One of the means which lead a person to acquire this trait is to prepare oneself for Divine service and mitzvot, namely, to not enter suddenly in performing a mitzva. For then, one's mind is not yet composed and is unable to think on what he is doing. Rather, one should ready himself to the matter and slowly prepare his heart for reflection.