If I had to commit to finish it before starting a book (or anything!) I'd read a lot less books overall (or try new things). This applies to a bunch of other things too. If I'm taking a class at the gym and I'm just not feeling it, I reserve the right to walk out at any time. And I totally do! If I had to commit to exercising for an hour or whatever I'd most likely wind up exercising *less*, not more. I'm only really comfortable going to a party if I know that I can leave at any time. I've let a hobby practically take over my life and then just stop. Maybe someday I'll return to it, but I don't know. I'm such a quitter.