Given it's a challenge, I just stick with it even if I don't feel like it. If I really just can't bear to read it, then I either DNF it (because let's be honest, if you can't be bothered to read a page or two, then you're probably not as interested in the book as you might think) or I just tack on that day's reading to tomorrow's goal with the knowledge that I'll either have to read more the next day or extend my deadline.

It's really about the self discipline over anything else.