Eli5: Why, if at all, does it seem like the years go quicker as you get older?

Question

I hear a lot of people making that remark, that the years go by quicker as you get older.
For me, at least, it seems like that’s only the case if nothing much changes in my life in that year.
To me, years seem to feel like they go slower if there’s lots of new/different things happening.

In: 348

Answer 1

When you are 2 and a year goes by to your 3rd birthday, that’s feels like you’ve lived 50% of your life. When you’re 40 and turn 41, you’ve experienced only 1/40th of your life pass. So 2-3 feels like a year, 40-41 feels like a week(ish).