Don’t finish what I started.

I was hoping to get some insight on not finishing things that I start. This is in regards to reading books or finishing an audiobook. I begin reading a book or start an audiobook that I am very interested in. Somewhere halfway I completely stop. Some context, I can read rather quickly but don’t grab all the information so I reread the sentence etc. this isn’t an issue for me because I am interested in what I’m reading. And with an audiobook, there’s really nothing too it but to listen along. So it’s not that I dislike reading as the reason to not finish a book. It’s been like this since I was younger. Any insight into why I keep myself from finishing a book? Again, they are books I enjoy and am interested in. Thanks for the help!