When you are in your twenties, even if you're confused and uncertain about your aims and purposes, you have a strong sense of what life itself is, and of what you in life are, and might become. Later ... later there is more uncertainty, more overlapping, more backtracking, more false memories. Back then, you can remember your short life in its entirety. Later, the memory becomes a thing of shreds and patches. It's a bit like the black box aeroplanes carry to record what happens in a crash. If nothing goes wrong, the tape erases itself. So if you do crash, it's obvious why you did; if you don't, then the log of your journey is much less clear.