According to Osho, the habit of looking back persists because, despite what you've heard from the awakened, you haven't directly seen the past as futile; you still prize it like a hidden jewel. Borrowed belief creates inner conflict; real seeing and dropping happen together. Until insight becomes your own experience (not imitation), the mind keeps guarding yesterday's garbage.
You keep checking the past because you still think there's something valuable there; once you truly see it's just trash, you'll stop looking.