What's worked for me (and the article talks about this too) is viewing my phone as a tool with a limited set of functionality. For me, that functionality is: calls, texts, Google maps, Spotify, Audible, podcasts, Uber, 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 checking) and no random internet browsing and twitter etc consumption. There are some blocking apps that might help with this, but the biggest thing is the attitude. 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 you need to go.