Ah, yes; I remember feeling old when I turned 20, nearly 60 years ago: because 20 years seems a very long time at that time of life, while now it goes by in a flash. Time accelerates & compresses as one goes on; so that I will swear on a stack of bibles that the 13 years of my schooldays (1937-50) took 10 times as long to pass as the 48+ years of my first marriage (1959-2007).