Most of the work of writing is just sitting down and writing. Of orienting the brain toward the idea that, whether or not it would prefer doing something else,

Most of the work of writing is just sitting down and writing. Of orienting the brain toward the idea that, whether or not it would prefer doing something else, it is going to write. You say "You can't "make" yourself come up with good ideas on demand". Which is sort of true, but first of all you have to get over the idea that the point of any one session is to produce a good idea. You have to open the channel and keep it open. That requires constant practise. And you have to stop being all precious about what comes out. There will be a lot of crap. That's not a bad thing.