Faith is believing the unseen even you haven’t seen it (Hebrews 11:1). It is not seeing the final destination, but believing you can arrive there by taking one small step at a time.
It is to have the light on your path, it is believing what that light tells you. Faith is obeying the revealed Will. It is not a mindless leap in the dark. It is an intention, willful obedience and confidence on a certain belief. It is not something you can produce, it is given.
This is kinda intricate thought: Faith is to see what is not seen, because the One who sees your unseen has seen it. So you believe the Pointer. It is believing the Map Maker because he had been there.
So, “just live by faith” is not inactivity and hopeless confidence that things will just happen and the sun will shine someday. Faith is action arising from a belief. It is a day-to-day obedience on a set of beliefs and having the confidence that this faith leads to life and rescue and meaning.