Anxiety and writer’s block come when you attach so much significance to your work that you start to feel that you just wouldn’t do it justice if you work on it while not in your prime. This is a stupid idea - nobody will do your work, but you. Just do your best, you will delete it if it isn’t good.
If you do something and delete it, that is not the same as not doing anything, even if you don’t ever rewrite or publish i.
And more importantly, if you don’t want to work, then don’t: take a hour off, leave your work in front of you and start start reading some random book, or doing something else entirely, untill something in what you are reading/doing reminds you of your work.