I know that itching feeling well, here's what's mostly worked for me: view your phone as tool with a limited set of functionality. For me, that functionality is: calls, texts, Google maps, Spotify, Audible, podcasts, and a camera.
That's it, no email (technically have the ability to send an email if i need to, but no notifications and no constant checking) and no random internet browsing and twitter etc consumption. I have some blocking apps that help with this, but the biggest thing I think is just the mindset. Twitter in line at the grocery store is no longer what my phone is for. Not that reading tabloid headlines is any better, but the main point is stretching out your focus muscles, getting rid of the urge to immediately grab your phone anytime there's a lull or hint of boredom in your life.
Overall, it's nice. Almost like being back in the 90's pre smart phone but also with a super powerful computer that can play any song you want/give you directions to anywhere when you need it to.