Here is how faith works for me, I believe anything is possible in fact just last night I asked god to please heal everyone in my house because they all are hurting and in pain. I have asked for such a thing many times and never once received an answer at least not a yes. Now was the reason that my prayer was denied because I lacked faith? well, that depends on how you look at it.
See I do not rely on the amount of faith I myself have I rely on two things my faith in him and his will. I mean he could so easily if he wished speak another entire universe into being by simply breathing knowing this about him I truly believe that with him anything is possible. See I ask for the impossible all the time I give him my faith in him I give him my request and I give him my willingness if he should need it the rest is up to him. I don't measure my faith based on my own faith or even the outcome of my prayer, the only deciding factor of the possible or impossible is if it is his will or not.
faith is not something I am lacking in because it isn't the amount of faith I myself have that matters it's the faith I have in him that matters, I can be lacking in faith and have only a tiny drop and yet that would not effect the impossible for me because my faith in him and what he can do is limitless, he only needs to give the green light and bam the wonders of his power and glory is there.
In the bible when Jesus roamed the earth he healed many many people and made the impossible possible but did you notice that he never took into account the amount of faith people themselves had but rather how much they believed in him? even the man who was lacking and said to help him with his unbelief was shown the impossible and he was lacking in faith and had unbelief but even with the small amount he had Jesus took that and did something amazing