When you get published (yes, that's WHEN. You have to keep pessimistic in this game) and if you're lucky enough to have gone the traditional route with an agent and publisher, it will fall on you at some point in your career to do some public speaking. This can include book signings, lectures, conferences, etc, and all goes towards promotion for your book. Most publishers these days expect it from you. When it comes to marketing, you have to pull your weight, too.
Well, even though I've cheated and only published one book on Amazon Kindle (go buy ;D ) my public speaking days are starting tomorrow. I got asked yesterday if I could attend my 10 year old niece's school and give a talk to her class about writing and about how, even if someone says that their story is rubbish, they shouldn't give up. I mean, where would we be now if we all quit after our first writing failures?
At first I was worried that my niece had made me out to be an international best seller to her teacher (one can dream, lol) but when my sister intervened and explained who I was, she was still more than happy to have me. Turns out I'm a perfect candidate to talk about not giving up - after writing 16 novels and only having one published...lol.
Anyway, I shall let you know how I get on later (for some unknown reason, I feel more nervous talking to this bunch on 10 year olds than I did talking to adults at our book launch. Is that normal??).