Ask HN: How do you stay motivated to complete your side projects?

How do you all keep yourselves motivated to work on side projects despite long days at school or work? I am a full time student and working at an internship and am having trouble staying dedicated to these side projects that I want to work on. At the end of the day after finishing homework all I want to do is go to the gym and then go to bed. I would love to hear what you guys do to keep yourself motivated to work on your projects.