Think of something you really enjoy doing. As a random example I'll pick "playing video games". Now, imagine you've been playing the same game for a couple day

Think of something you really enjoy doing. As a random example I'll pick "playing video games". Now, imagine you've been playing the same game for a couple days in a row. And you're getting kinda sick of it. Not that it's bad, it's got its good moments. You've just had enough of it, for now. Would you continue playing it? The answer is (hopefully): Of course not! You'd move on to something else you enjoy more. If the game was truly engaging, you'll come back to it anyways, maybe a few days/weeks/months later, when it captures your interest again. Since a few years this is my attitude towards side projects. The flipside is that you have to accept the fact that 99% of the things you start will never get finished. But that's ok, as long as you enjoy the work itself. Of course that doesn't mean there aren't difficult moments. But there has to be a genuine, intrinsic motivation, which is independent of shipping something. Keeping a journal/todo-list for every project (I use an infinite bulleted list like Dynalist) really helps, since you can just come back to a project anytime by looking at the end of the list.