There is a practical difference between believing in God’s faithfulness and remembering it.
Believing is what you say when someone asks. Remembering is what you have in mind at three in the morning when the situation looks genuinely bad. Most of us have plenty of the first and not enough of the second.
Here is a small way to build the second. Keep a note of the specific times God came through for you, with dates. Not the general story of your life, and not the things you cannot be sure about, just the ones you are certain of. Then read it on the days when you are certain of nothing.
Faith is not the absence of doubt. It is having something solid to stand on when the doubt arrives, and having it written down where you can find it.