The darkest room still teaches your eyes something about finding light.

Even the worst conditions teach you something about how to orient yourself. In the dark, you learn to notice the faintest source, to move by touch, and to use what little there is, and none of that skill goes away when the lights return. That is not a reason to be grateful for the dark. It is a reason to trust yourself in the next one.

Think about what you actually did to get through a bleak period, in practical terms. Whatever you found that helped, name it and keep it accessible. Those are the things worth reaching for early next time rather than at the end.