Reading a book, preferably a physical one, is a good way to get your attention back.
The problem in reading on smartphones is distractibility. You're a notification away from checking Instagram, email, or a text.
If you're going to read on a digital device, make it a Kindle. Its lack of functionality — just try web browsing on it — is its best feature.
Reading is an escape from the endless buzz of the digital world. It builds focus. In today's world, single-tasking is more important than ever.