Went abroad for a year when I was 15-16, was given a notebook time capsule thing in the first month to write my thoughts/hopes/etc. down on so that I could be shown them again at the end of my stay eleven months later.

I wrote something along the lines of "none of this matters" in the center of the page and then gave it to the supervisor to be put away.

When I got it back at the end of the year, I hadn't remembered what I'd written, so I was actually quite excited to open up the book. Instant disappointment.