Musar zu Tehillim 86:11

This is what king David prayed for saying: "teach me Your way, O L-rd; I shall walk in Your truth. Unify my heart to fear Your Name"(Tehilim 86:11)

The matter of holiness is dual. Its beginning is service [of G-d] while its end is reward; its beginning is exertion while its end is a [divine] gift. That is, its beginning is that which a man sanctifies himself, while its end is his being sanctified. This is what our sages, of blessed memory, said: "if a man sanctifies himself a little, he becomes much sanctified. If he sanctifies himself below, he becomes sanctified from above" (Yomah 39a).

However, it is impossible for a man to place himself in such a state. For it is beyond his ability. He is after all a physical creature, of flesh and blood. Thus I said that the end of Holiness is a gift. For that which is in man's ability to do is the initial exertion, pursuing true knowledge and continual thought on the sanctification of deed.