Emuna that one’s Tefilos have effect:
The Baal Shem Tov taught that the main aspect of prayer is for one to believe that Hashem fills all the worlds and through his prayer, the Shechina is elevated. He is also to believe that as soon as he verbalizes his request from Hashem, it is fulfilled. Now, although one does not always see this fulfillment, nevertheless it is simply because it is concealed from him. This means, that although the request may not be fulfilled in the specific area that he asked, nonetheless, it is fulfilled somewhere in the world. For example, if one requests from Hashem to remove a certain suffering from him, and he sees that the suffering is continuing, it is perhaps because he needs this suffering to refine him from sin, or perhaps it is for some other good outcome. Nevertheless, his prayer does effect some other area or realm of the world, and there is thus no prayer which is returned empty.
 Ben Porat Yosef Kuntrus Achron 127a; Keser Shem Tov 80