As weak as one may be in other areas, every person possesses the power to generate real, objective sanctity.
When a person vows to study Torah, his study will not always necessarily be on the highest level.
Nevertheless, he succeeds in creating sanctity, like the sanctity of the Altar, sanctity that rests upon a designated time or upon the commitment to study itself.
He promised, and now he sits down and fulfills his vow, thereby changing something within himself
Even if we cannot build a real altar, a vow enables us to build a small altar, and to exercise our ability to generate holiness in the world.
–Rabbi Adin Steinsaltz