If your co-worker could share how he did this, it would be appreciated (specifically, what apps/code needs to be run).

Not the coworker, but I've been doing this for a couple years. If you're on iOS, the simplest option is Voice Dream Reader [1].

It can read .epub files directly, along with text files and webpages, and integrates with Dropbox, Pocket, Gutenberg, etc.

On Android, you can get Voice Dream Reader (though it has less features than on iOS) or @Voice Aloud Reader which is free [2].

[1] http://www.voicedream.com/reader/

[2] http://www.hyperionics.com/atVoice/

It also works reasonably well for academic papers as PDF. Equations get butchered, of course, but overall it's not bad (you can set PDF margins so that headers/footers are not read out aloud on every page). I use it to proof-read my own writing, it helps you spot things that spelling/grammer checkers miss.

I have been doing this on Android for a few years using Ivona, FBReader with the FBReader TTS+ Plugin. I got Ivona (beta) from the Play Store before they were bought by Amazon - it looks like Ivona voices have since been pulled and are no longer available.

For Android take a look at this: https://www.youtube.com/watch?v=MAHg31ucDhY

Google's "cloud-based" TTS (not the local one, which was terrible) on the Play Books app was pretty good even years ago.

However, it was unusable because it would stop as soon as the screen would turn-off. Other ebook readers' read-aloud features worked with the screen off. So thanks for nothing Google!

It used to stop; it's been well-behaved for at least a year. I use it daily!

That's not my experience, as I can turn off the screen and still read the book. I tested it just now.

Android is different for each person