I have an idea that putting some effort into making the things I _want_ to accomplish (e.g. another MOOC course) more readily accessible might make it easier to form a habit around consuming what I _want_, rather than mental candy.
https://heyfocus.com/ <-- Focus, lets you block sites. Start out just blocking everything from 9AM to 9PM
stay logged out of websites. Every time you want to use a site you should have to log in
https://addons.mozilla.org/en-US/firefox/addon/history-autod... <-- this website will let you block things from your history. This prevents the "type n -> press down -> press enter to get to hacker news".
I'm typing this here so it's not 100% effective but I've found that after going sessions cold turkey I start to stop caring about the churn of news (especially for twitter).
Prune people you follow on social media. Especially high volume posts/low effort stuff. Not worth it.
I've found that using RSS feeds help a bit because you can only look at something once. No "purple link syndrome".
Good luck, I'm still struggling but I feel much more in control of my life compared to even 3 months ago after getting burned out like we all are. Especially from political twitter (just read the news on a normal website, it's fine to be 6 hours behind).
It's even shorter as you can skip the "press down" step. At least in Chrome and Firefox.