Reading habit is really useful and important to live a good life with the sense of understanding things in a better way. With the same habit, also we need to take care of our eyes and mind.
I always prefer reading hard copy of the book than reading on mobile phone, even sometimes I use my laptop which has a really good display.
Sticking your eyes to the smartphone for reading purpose could be rally harmful for the eyes and the brain as well. Online you could easily get the hard copy of the books if you wish to read any book.
If you are traveling to somewhere then you can use your phone or tab to read something. While staying at home try to have book rather than reading on phone.
You can easily get distracted while on phone but you can spend quite long time on books because you will not have any kind of distractive tones or notifications there.
If you have any suggestions let me know...