Breaking one’s will comes about through actually separating oneself [from one’s desires], simply, not doing what one wants. In this way, the person’s spirit of desire is broken. A person’s natural, animal powers grow stronger when they are used; [so too, they are weakened when they are not used].
[To explain this concept:] The reason one’s natural, animal powers grow stronger is that one uses them. As Rav stated (Berachos 61a): The yetzer hara is like a fly sitting between the two entrances to the heart. זבוב, Hebrew for “fly,” has the same numerical equivalent as טוב, “good.”1 The yetzer hara tells a person that it seeks his welfare. Therefore, at the outset, it does not attempt to lure a person into severe [transgressions], only light matters. (As is well known, [the yetzer hara exerts its influence on a person in] a progressively increasing manner.2 It is described as a passerby, then as one who stands, and then as one who sits [and takes up residence]. At the outset, it flits by, almost haphazardly. [Nevertheless, it attracts attention.] Afterwards, it remains for a while; [it “stands,” i.e., like a guest who stands, its influence is intermittent]. Afterwards, it “sits,” [i.e., it is at home within one’s personality and has an ongoing influence].)
[To apply these concepts on a personal level:] In the beginning, the yetzer hara shows one the way the world looks at things; that worldly matters are necessary. This cools off his [spiritual ardor]. (It causes him to accept the way the world looks at things: what the world thinks is attractive, what the world thinks is distasteful.) It becomes plain and clear that involvement in business activity is necessary.3 Once it is accepted that business activity is necessary, it follows that the business must be conducted in this and this manner. This is the way the world looks at things. The yetzer hara tells him that for [the success] of his business, he should conduct himself in this and this manner, [and he listens]. As we see in actual fact, there are certain people whose emotional characteristics change entirely when it comes to business matters; they permit themselves to lie, and the like.
[Firstly,] through such conduct, one enters the domain of the yetzer hara, [i.e., it exerts a dominant influence]. The person’s heart completely forgets the truth: [that success comes because] “G‑d, your L‑rd, will bless you in all that you do.”4 [Moreover, this leads him] to become a person of undesirable character, one who employs falsehood and deceit. He works tirelessly at his business to the extent that he cannot establish fixed times for Torah study. Even his prayers are not fixed and firmly established [in time and place] and they are recited quickly. For what dominates his character is the yetzer hara and its worldly way of looking at things.
Nevertheless, since the animal soul has not entirely taken root, it still agrees that the person may pray. Nevertheless, in the midst of prayer, it casts sparks and stones, i.e., foreign thoughts, into his mind. At times, the person remembers that now is not the appropriate time for such thoughts because it is the time of prayer. But then the animal comes back and overcomes him with the argument that the matter is very important, and if he profits, he will be able to give tzedakah.
Moreover, aside from the fact that [the pursuit of profit] disrupts his prayer, it also prevents him from establishing fixed times for Torah study, explaining that he is a business man. [Therefore, instead of studying,] he will give tzedakah.
In this way, the yetzerhara leads him lower and lower, Heaven forbid, until he accepts the outlook that for the sake of his business, he must work tirelessly. Accordingly, he cannot establish fixed times for Torah study because the time is not convenient. He walks around in chaos, spending his days and years in emptiness until, over the course of time, he looks at his inner character and is shocked: How could he have reached such a situation! [How could] his natural, animal powers have become so strong and his spiritual powers so weak!
The explanation for all the above is: [because the person’s natural, animal powers] have been employed to such an extensive degree. But the opposite is also true. Just as one’s natural powers become stronger the more they are used, the spirit of one’s natural desire is broken when they are not used. The intent is simply not to carry out one’s desires… simply not to do.
[A point of clarification is necessary. There are some who] err in their Divine service and think that if they are able to control themselves and bring themselves to engage in a [physical] activity (e.g., eating, drinking, speaking, or the like) and yet, not invest concentrated intent,5 they have already refined and purified themselves. Aside from the fact that it is highly doubtful whether they have achieved such self-mastery, more importantly, they have not accomplished the fundamental objective: breaking their will. For it is by breaking one’s will that he destroys the spirit of desire.
Summary
Breaking one’s desire comes from separating himself [from indulging in his desires] in actual practice.
Proof is brought that one’s animal powers and animal soul become stronger when they are used. [From this, it is understood that the opposite is also true. By not acting on one’s desires, he breaks and conquers them.]