I appreciate the comments, but I think I'm just going to set this ambition aside for the time being.

Writing is kind of like cooking; if you think it's not good enough, maybe you can add a little something to it to make it better. And if you are not happy with a rough draft, you have the opportunity to revise it as much as you like. (Kind of like making a dish over and over to get it right.) Maybe jot down images or feelings you want to addresss. Or find a picture/painting that you like and take notes on how that makes you feel. It's all up to you, and no one else has to see it, until you choose to make it available.

Just keep plugging away! Try to set a time, & a particular amount of time, just for writing. & keep to it, even if nothing happens for you at first. Good luck!