Read and finish print magazines or ezines.

Any genre. 

They can be the most popular magazines from big publishers like BHG or Men's Health or Popular Mechanics, or they can be fiction magazines or even scientific journals. Any genre of periodical magazine works. 

If you want to challenge yourself you can usually access less popular local titles or even international magazines through your local or state library. 

You might also consider getting magazines for different types of audiences, to get a more diverse reading experience. 

I want to challenge myself to read magazines because they seem much better for my brain to read during those moments when I can't get into a full book, and I don't want to scroll and turn off my brain. They also have the benefit of being finite unlike infinite social feeds that are hard to stop.