I had a great writing teacher back at Hunter College, Professor David Winn, whose special gift in teaching was this: He cared that we wrote. It was important to him, if to nobody else; if nobody else was interested in what we had to write, he was interested. From him, I got the idea that it really made a difference in my quality of life, as well as the general quality of life on the planet, if I actually sat down and wrote something, whether or not it was for public consumption.
I actually care that the writers I know write, that the artists I know make art. I know how fucking difficult it can be, and I want them -- you -- to know, it makes me happy that you do it. It makes it easier for me, selfishly, to have more comerades-in-arms, and as a reader, and someone who's perpetually curious about what goes on inside people's heads, I need your writing and art to keep me from dying of boredom. Writing and art make the world better and happier, so thank you for doing it, as difficult as it may be.
I got another great piece of writing advice from Eric Maisel's proposal writing book, which was to recognize how much anxiety it produces when we write or make art, which is why we fidget and can't concentrate and often wind up more frustrated than when we sat down at the desk, vowing never to try that again. Then you have to recognize that NOT making art is also anxiety-producing. So you just have to choose one form of anxiety over the other. Writing can bring up very potent feelings, some of which are deeply upsetting, but it's worth it, if you know that you'll feel better when it's done, and you'll be spared the anxiety of not writing. I use this one every day to talk myself into getting to work.
I don't really know if anybody can "teach writing," per se, but I do think you can help inspire people to work, and to develop good habits -- keeping a notebook, setting aside quiet time, learning how to push on rather than stopping and going back and judging too soon. How to calm your expectations, so you're not staring at a blank page, going, "Where's my bestselling novel?" How to surround yourself with healthy support.
When people say, "I need deadlines to write," often what they mean is, "I need to know that another human being is going to read this and react to it, or it's going to feel futile." If that's true for you, then find that human being; be that human being to someone else. It's not futile, it's vital. At least, it is to me.