I've been developing software for over 40 years now (35 years professionally) and I still love the idea that I can create something from nothing. I always have a couple hobby projects that I can spend a few minutes on ... things that stretch my skills or that involve a subject of interest outside my day job. I also make the software I write for work more fun by treating it link a craft ... if you see art in what you're doing, even mundane programming can be fun. Curiously, altering software to make it testable and writing the tests is one of my soft spots.