My husband and I joke around often, saying if we don't write something down immediately while we're thinking of it, we won't get it done - - because the tv keeps telling us we're getting old and that part of getting old is becoming  forgetful.   

I've actually been writing things down and making lists my whole life, and I wasn't old at 16.    There are lots and lots of good reasons to write things down.  Keep reading:

https://www.lewrockwell.com/2018/06/no_author/want-to-boost-your-productivity-and-clear-your-head/

I think part of the reason I got started writing everything down is because I had a school project in 9th grade to compile a family history, consequently I could never remember all the details so I wrote them down.  By the time I was done I nearly had a book.  I didn't just do a family history from one side of the family, I did maternal, paternal, plus the greats and the great-greats from both sides.  I went back a loooooong ways, and let me tell you, ancestry dot com doesn't have a clue about my family history, at least not as I was able to get it from REAL family members who were still living at the time.  My older sister (now deceased) used to pore over the crap she got from ancestry in it's early stages in the mid 2000's, and I've since looked at her info from them.  It's about as wrong as it can get.

So please, don't waste your money on ancestry crap and dna tests from 23 and me and junk like that.  It's all pretty kinda sorta bullshit and bogus.