In 2014 I started keeping tracking of the books that I read.
When I'm reading a book I love, I can't stop. I can't put it down. I'm in a flow and I have a constant desire to get back to it and I'd happily spend my entire day reading. Given that, what's preventing me from reading 50 books a year? The common answer is time but that's not it. It's avoiding the momentum killers that slow reading down.
Choosing a book can kill my momentum. Despite having piles of unread books lying around me, I frequently find myself not wanting to read any of them which irks me to the point of not starting a book. I'm the true embodiment of Tsundoku -- a Japanese word meaning acquiring reading materials but letting them pile up in one's home without reading them. Either way, reading momentum lost.
My next momentum killer is reading a book but not enjoying it. I try to trudge through out of some mistaken sense of loyalty. I hope that I'll eventually start to enjoy the book or that my future self will regret a critical learning that would have emerged further into the book. The net result here is that I stick with a book I'm not enjoying, my pace decreases and the amount of time until I get to my next book, one that I hopefully can't stop reading, expands.
Given these, what are the keys to avoiding losing the big momentum? It's really pretty simple. Read books that interest you now and stop books that you're not enjoying. There are too many amazing books out there to waste time on a book that's slowing down your future reading.