My bf told me he started writing diary since when he was in middle school or high school.
I've fogot the exact time.
And he used to write diary everyday!
Now since he is busy, only do that once a week.
He said, so far, he has had over 20 books of biary.
When he told me this, I thought he was a very sensitive person
and started to falling for him from then, hehe :-)

But one point, never share your diary with your partner.
Indeed, that's how my bf broke up with his first girfiriend.