If you don't know what to blog about, but you're fairly good at typing, I recommend it. (I'm not sure how it would work if I had to hunt and peck for each letter - my brain-to-finger motion is pretty seamless at this point.)
Though really. My mother had 60 words per minute on an old-fashioned typewriter, not even an electric one at first; probably with a sheet of carbon paper underneath and working from shorthand dictation. If I didn't have a Delete key up there within easy reach of my right little finger, this would be a whole 'nother ballgame. She was a proper secretary, like the sort they had in Mad Men. (I wonder if she's ever seen Mad Men? Must ask her. I bet she'd love the clothes but she'd spend her whole time telling me how it wasn't like that in The Bank.) (There is more than one bank in the country, but apparently not when you worked there. Everyone, according to my mother - that is, all the unmarried ladies in Dublin - either worked in The Bank or Guinness's. That's just how it was in the 60s. They were also all in either the tennis club or the golf club.)
I've used one of those old typewriters - my mum still has one at home in its own lovely wooden case. You have to bash down each key with the force of a concert pianist going for broke on Beethoven's Ninth, and you have to sit up straight and hold up your wrists too. None of this slouching over the kitchen table with my elbows all noodly, like I'm doing now. And I imagine it would be pretty hard to take your typewriter to bed with you and type on your knees, cosily wrapped up in a dressing gown, as I have been known to do. The people who habitually blog while on the loo would have a bit of a problem too, even leaving aside the problem of how to connect your manual typewriter to the Internet and how you might insert a hotlink.
I suppose what I'm getting to is that blogging is so much a product of this time, and I imagine it will be superseded by something new and improved in a few years, so that our children will read about it in the footnote of a history book and say "Oh yes, my mother used to do that," and they'll wonder how we managed when life was so hard and laptops were so unwieldy and you had to use all the fingers of all your hands to put words on a screen. Maybe they'll all be vlogging, or they'll attach electrodes to their brains and mind meld, and the whole Internet will be In Your Mind all the time...
If I had lived in any other century - or other few decades, I suppose - I might have filled diaries with my blathering, but I'd more likely just not have bothered. Blogging gives me a tiny, supportive audience - just enough to keep me writing, not so much that they become critical and put me off. The fact that I'm just one of bazillions of bloggers means that if someone doesn't want to read what I'm saying, they can easily go elsewhere. No harm, no foul; no money or time wasted; no skin off my nose. I get the validation that keeps me writing, I get the creative outlet and outside connection I need in these years when former at-home mothers would be isolated and inward-looking (back to Mad Men, and I've only seen the first season so don't go spoiling me). I get to feel like a writer, without all that character-building, soul-destroying rejection that "real" writers have to go through.
Because if you write, you're a writer. If you write for an audience, you're a writer. If you write a blog, or a book, or on the back of a napkin, you're a writer. If you write because there are words inside and you want to get them out, on paper or on a screen, or somewhere in between, you're a writer.
I blog because I want to write, and this is where I get to do it.