It’s the medication! I’ve been on many different anti-psychotic medications and they all seem to give their own level of motivation. It sucks! Dunno if you want to change your meds though so you can have fun again. I started a topic about the exact same thing then afterwards I scrolled down and saw this one too.
Maybe quitting might not be a option, but maybe get to a lower dose? If it has been a long time since you tried reducing your dose it might be worth to give it a try.
When I cut my dose in half it made a world of difference. I’m still struggling some with motivation, but I don’t have apathy anymore.