When one refrains from committing a transgression, it may be because one simply has no desire to commit such an act.
In contrast, it may be that one is able to refrain from committing the transgression despite his desires.
The Midrash articulates this line of thinking: “I do have a desire for such and such, but what can I do, since my Father in heaven has ordered me to abstain?” (Sifra, Kedoshim 9).
The general conception of holiness is, in a certain sense, “I have no desire” -I cannot do it; I have an aversion to such a thing; it is simply out of the question for me to stoop to such a base, low level and commit such a sin.
A story is told of a rebbe who claimed regarding one of his Hasidim that the reason he does not sin is simply pride.
For this Hasid, it seemed degrading that an exalted personality such as he should demean himself through sin.
There is a clever (though certainly not straightforward) explanation of the verse, “The wicked crows (hillel) about his unbridled lust” (Ps. 10:3):
Does a wicked man resemble the great sage Hillel?
The answer is that even a man as distinguished as Hillel the Elder is capable – when obsessed with “unbridled lust” – of bringing himself to a state that is so indecent that he reduces himself to the level of the basest of individuals. This can be seen in the case of all sorts of desires.
A person can be distinguished, admirable, respected, and highly regarded; but when he is overcome with passion – suddenly, all the eminence peels off him, he debases himself and becomes a kind of four-legged creature, or even something lower.
Rabbi Adin Steinsaltz