It seems just yesterday I was in my mid 20's, the following 25 years went by much much faster then my first 18 or so. I'm not looking forward to finding out how fast the next 25 +/- will go.
I feel like I'm accelerating through time. Every day / week / month / year / decade, goes by faster than the previous one. Maybe I'm just getting more sleep than I used to in my younger years.
But if you think about it, every second you're lucky to live, makes up a smaller and smaller percentage of your total accumulative life experiences, so of coarse it's going to be perceived to go by faster in relationship to time.
If you put a young child in timeout, 5 minutes makes up a lager portion of that kids life, then someone who is much older. For a child It can seem like a eternity. A older adult would enjoy the quick break and wish it was longer.