I just finished with a side project. I knew going in that I would lose motivation for reasons left and right, even though it's the right project for me to work on. In order to keep up my motivation, I started "Side Projects Dinner" - I would make dinner for my friends every other week, and they would give me feedback on my project. It worked great, and we've had quite a lot of fun. And of course, my friends are also getting feedback on their own projects and thinking of new project ideas. Highly recommended!