Personal Writing Instruction

Where to begin on this subject.  It's been decades since I began to write.  It's not something I do on a regular basis.  I would like too and I have tried many a time to write in a journal over the years.  It seems that writing journals are more of the norm now than way back when.  I remember in 1st and 2nd grades we copied sentences that the teacher wrote on the board.  In higher grades, I remember practicing vocabulary and having to use the word in a sentence or two.  It seemed like any type of paper I had to write whether it be a book summary or a research type paper I always wrote too much information.  I had a hard time cutting it back.  But I also found it always hard to start.  It was overwhelming for me.  I still get that feeling today.  I am much better at writing letters than anything else.  Maybe it is due to writing what I know and feel.  I also recall having to do re-writes until the end of time.  This is when it was legal to use red pen to correct students.  :D  As I am writing this I am trying to figure out how I can make sure my son is a writer.  He's only 5 but why can't he start a journal?  I should sit down with him 3x a week draw and write simple sentences with him and place items of interest to him (stickers, cut out pictures, etc) in a little journal.  My hope would be for him to make it a habit unlike what I have done - when I find the time!