I feel that pain! Honestly working with monoliths and older and larger projects is very demotivating. Now, I'm not saying that you need to go full on microservices either, but working with a few smaller services instead of a single huge one has been a game changer in my experience!
I'm not sure I ever want to go back to the loop of changing some code and then having to wait minutes for the app to launch locally just so I can test something and realize that it's still wrong.