We strive with God not for the purpose of making him kind or generous but rather to gain his attention and make known to him the extremity of our need (cf. Hos. 12:3, 4). Our aim is not to wrest favors from him but to realize his purposes more adequately. He already knows our needs, but he wishes us to come to a full realization of these needs as well before he deigns to act to fulfill them. He wishes us to be earnest in our requests. When God chooses to wait before answering our prayer, we too must wait — sometimes for a long time. There is the patience of prayer as well as the restlessness of prayer.
from Donald G. Bloesch, The Struggle of Prayer, p. 135.