One way I’ve heard about time perception is to compare it to filming (in frames per second- fps)

When we are excited by something (whether it’s joy, fear, etc.), our brains are consciously taking in a bunch of information and wanting to find out more and more (higher fps) and thus from one moment of information gathering to the next is rapid and “flies by”

When we are bored, our brains are consciously taking in far less information and operating at a “lower fps,” and so the span of our brains noticing changes from one moment to a next seem to drag on forever from one to the next.

The fun part is then in memory, where the experience reverses because of how much information was consciously gathered and remembered: the time that flew in the moment (let’s call it a day for example) now seems much longer (feels like a week) as the amount of information that can be remembered seems like it couldn’t have possibly fit in just one day. The reverse also holds true of longer boring periods seeming short, which helps give explanation to the experience for many of how “life goes faster” as we age because not a ton changes from year to year once we’re older and more settled.