I think the recent link on HN (
https://www.theguardian.com/technology/2018/mar/04/has-dopam...) gives us a clue. Consuming gives us instant gratification in the form of a dopamine hit. Whilst producing unreliably gives us a hit only once we complete a significant chunk.
I have been aware of this dynamic for a long time and by recognising that we develop an addiction to dopamine we can take the sorts of steps that are applied to weaning off any addiction. There are numerous articles on the interwebs on different processes. You might need to experiment to find the one that works well for you.
The other thing that I do is to "chunk it down", i.e. pick one small, manageable piece of a task. One that takes me no more than 90 minutes and do that. Once completed I do an affirmation and take some time out. Then tackle another chunk.
If you have trouble concentrating for 60-90 minutes then I would suggest embodying some of the strategies in "Deep Work" by Cal Newport.
I find that making a short (3-5 item) ToDo list each evening for the next day helps too.
Finally, it is best to recognise that there are many interlocking pieces to making these changes, and it takes time. And don't beat yourself up when you drop the ball. Take some time out and muck in again.
I no longer have any social media apps on my phone or notebook, only on the desktop and check them at most once a day, sometimes not for several days. I leave my phone on silent and only return emails once or twice a day. But HN -- that is the one "luxury" that I browse for a few minutes between chunks.