For the OP.
If you are a music fan you can find websites that will have a variety of songs that are at a particular tempo. You can pick out 2 or 3 songs that are at 80bpm and sing them to yourself to try and maintain your desired cadence. (Please do this using only the 'inside your head' voice--the rest of us don't want to hear all that!)
The problem you might face if you are as old as I am is finding the website that lists songs you would actually know. Most of the songs I want to sign to myself were recorded before time was invented.