> One thing I've never really recovered is the passion I had for side projects. Worse than that, I can't actually think of anything worth building, or even tinkering with, which is sad, as spending some of my free time on side projects was something I really enjoyed.
If you don't enjoy side projects any more, don't force it.
Better side projects would be something offline like improving your personal fitness, learning a new (non-computer) hobby, leveling up your cooking skills, and other real-world skills.
Forcing side projects on top of a day job is a recipe for returning to burnout.
Also, have a hard look at what it is you enjoy about side projects. I found out I like the figuring out things part of it (including talking to potential users and solving their problems), but everything after that (marketing, maintaining, improving) drained me.
If you don't enjoy side projects any more, don't force it.
Better side projects would be something offline like improving your personal fitness, learning a new (non-computer) hobby, leveling up your cooking skills, and other real-world skills.
Forcing side projects on top of a day job is a recipe for returning to burnout.