I wish I had your problem; mine is to find books I want to read. I very often re-read ones that are already on my shelves, for lack of anything new. However, this suggests a possible approach to your issue: When buying a book, check whether you are actually and genuinely excited to read it, so that you will open it the minute it arrives from Amazon. If not - put it in a "maybe later" pile. If it's more a case of "sure, sounds good" or, even worse, "I want to signal having read that", then give it a miss.

If you need to read stuff for work or for Serious Social Purposes like a book club, then treat it like work - set aside a certain time of day or week, and during that time, read.