I kept a diary when i was a teenager ay school and going to uni for 5 years ( 16-21). I found it last year and could not believe how miserable life was sometimes- all that angst that you can completely forget. Found it quite helpful having a teenager myself. Funny thing is, some thoughts worries are the same 30 years later, and some seem so childish - you do forget. I kept a diary - of sorts- the first few years of motherhood as I could not believe how hard it was and it helped enormously with a second child to look back and see the records of the first and remember what happened. I certainly would not want anyone to read either of them.