Keeping a Journal--do you?

In my short story series The Caldecott Chronicles (out November) I write about an Earl who keeps a journal detailing the invasion of his property by the undead in the summer of 1896.
His journal is written on-the-go and contains graphic sketches often splattered with..slime, guts, cordite... ink. Here's one below--there are twelve in total. [image error] Dr. Fotheringham needs another brain...
Apart from his precious Purdey shotgun the journal is the one thing he treasures. 
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Over the last few years I have (really) tried to keep a journal of events and my writing. I think I imagined I would sit down one day when I'm old to re-read them... after which I would die with a sickly grin on my face.
Like all journal keeping for me though whether written on on-line on paper (!) my efforts are sporadic.I am the same with photography. Sometimes I'll take lots of photos and lots of notes and then months will slip past with nothing--I just forget. 
This article from the NY Times shows how a reporter found a journal written by a girl in 1934 and then tracked her down in Florida aged 96. 
Why do you keep a journal?  Is it digital or paper?Do you mind when others read it? (because they will!)