Inner strength is a difficult asset to audit, because it can't be inspected in advance. It only ever appears mid-use.
Ask anyone about the worst thing they've come through and you'll usually get some version of *I don't know how I did that.* They didn't know they had it either. It wasn't stored anywhere visible. It showed up when the situation asked, and dissolved back into ordinary life afterward.
So a shortage of felt strength today says nothing about supply. You've already spent some of it, on something you'd have called impossible beforehand. Whatever comes next will find the same reserve waiting.