OK, friend, why are you here? It’s read a book day.
How can you do that surreptitiously while at work? I can’t suborn such behavior, but you already know about this:
You probably have seen this:
https://itunes.apple.com/us/app/free-books-ultimate-classics/id364612911?mt=8
You might find this new:
https://store.kobobooks.com/p/free-ebooks
And you doubtless have this already:
(I mean, c’mon, it’s literally “freebooks.com.”)
So, open one and read a page. Just a page. It could even be this page:

Enjoy, fellow Pheniacs!