I "retired" like MMM did, in that I retired from my main, full time profession, and have no intention of going back because I physically can't.
I can afford not to work, but I like work, so I'm constantly taking on projects. Some of those projects are compensated, some aren't. I only take on projects I enjoy. I easily walk away from the ones that I stop enjoying.
I enjoy working for free when it makes sense, but I HATE doing work for free when it's just a business entity trying to take advantage of me. So for that work, if it's interesting, I insist on fair compensation, but what's fair isn't some default amount I insist on working for. If it's a $500/hr job, then I'll expect $500/hr, if it's a $30/hr job, then I'll expect $30/hr. It depends on which skills I'm using and what the industry is.
That said, I'm doing another degree right now, which will lead to another career, so even though I have some paying projects at the moment, I won't consider myself "unretired" until I'm back to having an actual career. Not just work that I move in and out of at will.
All of my definitions for myself are 100% arbitrary, like everything to do with defining what "retirement" means for anyone.