How Do We Know Time Has Passed?

Imagine you're playing a game, and you look at the clock, it's 12 o'clock. You go to bed and wake up the next day, and now it's 1 o'clock. That’s how we know time has passed. But what if there was no clock? What if you were just counting your breaths or your steps? We use things like our memory, changes in our body, and even things like the sun moving across the sky to tell time has gone by, sometimes without even noticing.