Is this work or non-work?

If its work then have an honest conversation with your manager and get better at saying no (or, at least, not saying yes). If necessary, leave and find a better working environment.

If these projects are filling your non-work life - otherwise known as Your One and Only Life - then recognise that this isn't sustainable. Just stop, give it a few weeks, go for walks, peoplewatch, breathe. Then choose the project that engages you the most, and which you can fit into a healthy part of your free time, and focus on that. Park the rest.