I mean, barring some large event, it'd be hard to change one's relationship to one's work/life/activities overnight, and even then the large event only accelerates the process.

I'm just using injury and aging as examples for events that help us to see that changing what we find joy in is possible.

Another example could be the first time you play a game in a genre you don't typically play and find it so completely compelling that you don't understand why you ever avoided the genre. Same with genres of writing, a single auto-bio/history/fantasy/sci-fi could open your eyes to the entire genre. But that's just more evidence for finding joy in things you previously did not find joy in.

So, the idea is that if it is possible to change what we find joy in, if there are things we must do that we typically view as burdens, it is possible that we could come to enjoy those things in the same way that we've come to enjoy all the things we've ever come to enjoy and will ever come to enjoy.