The size of the struggle is commensurate with the size of the goal. If you are trying to overcome the greatest challenge in your particular life, this is your biggest its set of adversity ever. The likelihood of success is also probably the lowest it's ever been before. To say that you can accomplish something like that without faith seems to be unlikely. There's no proof that you're going to make it happen. But you feel it and you buy into that to such a degree that you're willing to do it anyway.