Well, there are all kinds of audio files one can get.
The type I enjoy are OTR [Old Time Radio] programs, most of which are free. These predated television, and are either 30 or 60 minutes long. They make for some terrific entertainment.
Other members enjoy hearing actual books, but I only occasionally will listen to a novel. I much prefer to read it.
If you have your iPod (mine is a Classic gig 80 unit), then use iTunes to load them into your Library and sync. Be careful, of course, with syncing since you don't want to delete your entire library.
Most often, I'll just download a whole gig of mp3 files and load them onto my Kindle tablet, since the process seems easier.
If you have a tablet [non-Apple], then just load them into a file into a folder and find a good mp3 app that will read them and keep a bookmark for you.
Here are a ton of free mp3 files of Old Time Radio shows:
https://archive.org/details/oldtimeradio
I'm downloading the program "Dimension X" right now. It's 1.3 gigs of 50 shows total. That's 25 hours of listening pleasure.