So, why does time fly by as you get older? When you are younger, you have more novel, new experiences. You see your mother for the first time. You learn your first language. Everything around you is new information. When the brain puts together these new details, they seem slower when you look back on them. When you age, your understanding of the world is larger. But because you are constantly surrounded by the usual family, school and experiences, details aren’t taken in so intricately. This makes entire days seem like fleeting moments!
According to this psychological diagram, if you turned 80 - looking back, the middle of your life will appear to be your 20’s!
Moral of the story: Do something new every day to make your life seem longer and richer.