You say to finish things...but I can't even start. I was a writer as a kid, and I finished and started things constantly. My confidence slowly shattered as a teen. I'm now in my 20s and I'm a nervous wreck. I long to write, but the thought of it makes me so anxious. I've created a legitimate fear. How might I overcome this?
I’d suggest two different ways, very different from each other.
You could tell yourself it doesn’t matter, and start finding out how to write for fun again. Give yourself an hour a day to write in: no phone, no internet, no reading books or talking to people, no Tumblr, just time to write in. And in that time, write whatever you want, or don’t. A poem. A description of someone. A memory. A sea-shanty for seven morose pirates and a raccoon. Anything. Just give yourself time to write and find that writing can be fun again.
Join a writing group. The kind of group, online or in real life, where you have to produce work to be read by the other people in the group. Where not writing will have consequences, even if the consequence is that people will be disappointed. So there’s enough external push to conquer the anxiousness on your part.