I feel what’s really intreresting with side projects is momentum and sense of urgency. I rarely have side projects that have a real dead line. However, I image a sense of urgency to build momentum. Once I am spending every free hour outside of work on my side project, it’s really hard to suddenly take one day off. What’s interesting is that this momentum, I think, creates intrinsic motivation. If you want to be productive you should learn to harness this. However, of course balance is always needed, even though I don’t consider all side projects to be part of “work” in the work life balance.