Think about what you want out of working on some side projects. If you think it's important for your career or because there's an itch you want to scratch, etc. you'll make time for it. If you think you're doing it just because you feel you _should_ be (because of something-something-#hustle-#grind), then I would think twice about spending your precious free time on writing code in your free time for the sake of writing code in your free time (or trying to monetize your free time!). You own your free time and you should fill it with the things you want to do as part of a balanced, enjoyable life.

I write a lot of code outside of work. I have some sort of compulsion to do so, and have numerous passion & open source projects I work on. They pretty much all scratch some sort of itch for me personally (either creative or mentally). This keeps me motivated because they're all stuff _I_ want to do and mostly not things I feel like someone else wants me to do or I'm making myself do. I don't worry about going months between touching some of them. Some weeks, I don't feel like touching any of them and will spend most or all of my free time on other stuff.