Funnily enough I was a huge, huge book hoarder until I started working at the library (I also read a whole lot more before I worked there, but that's more to do with lack of time now rather than specifically library related!)

Being taught how to curate and weed a collection properly, and the reasons for doing so, was a big eye opener. I trimmed my personal collection back considerably a few years ago - at that point it was spilling out of the verandah room and trying to take over the living room. This time was a bit easier, but I was still surprised by the sheer volume of extra books that had crept in.