There's a saying about landmarks in your life (at least as much is true in America):
18 You're old enough to be considered an adult.
21 You can now drink
36 You can legally sleep with someone half your age
42 You're now twice the drinking age
After that is when your hair falls out of your head and into your @$$ and the warranty is pretty much out.
I would personally say one more:
Your golden year being the year your age and the day of the month of your birthday match, any number between 1 and 28,29,30,31 depending on month and in one case, year. (I.E. 26 on the 26th