In the Emily books, Emily writes a ten-year-letter to herself, written on her 14th birthday and to be opened on her 24th birthday.

I copied her idea when I was a pre-teen and I wrote several ten-year letters to myself. I was rummaging in my room tonight and I found them - I should have opened them on my last two birthdays. I'm surprised that I forgot to. I vaguely remember what was in them, but now I find myself lacking the courage to open them. It feels too sentimental.