I've found that sometimes the hardest issue is getting mentally unblocked enough to find a problem that seems approachable. One of the best ways I've found to prompt you is to start browsing libraries till you find some that imply a goal you might enjoy. My last fun personal project was making a command line AppleTV remote with a lib for doing such. I'd been so burnt out till I saw a random link to the lib, and it just sucked me in.