I change cables every 5,000 miles when I do a major service, paying a little bit extra for a decent quality cable, and I change the outer every second service.
You've got a retirement project, if you want it - I'm keen to take off the cheap and nasty 3x7 Alivio and replace with a XT M8000 2x11. £299 on ChainReactionCycles - worth more than the bike, but I like the bike frame and it likes my back!
This guy made a nice job of his - although I'd want the 2x11 rather than his city setup
https://www.bikeforums.net/hybrid-bicycles/900247-...