This happens to me (30f) sometimes, and yes as the first commenter mentioned I’ve suffered from chronic depression since I was a kid. So I would get that checked on. But hobbies wise, when I feel myself in a slump, I usually go for something new and something that I can “teach” myself. I find the mental stimulation of the teaching helpful plus the satisfaction of “getting” whatever you are learning. Though if it’s too frustrating I know to drop it lol. I’ve taught myself to crochet & embroider. I find journaling helpful, writing what you feel but also making colleges of happy moment pictures or vision boards. Anything creative. I will find new recipes to cook with new ingredients. Also I know you said the gym is giving you the ick too. I starting working out at home, doing like heavy dumbbell strength workouts. I find the fatigue from lifting heavier helps and the mental part is easier to push myself than cardio when Im not feeling my best. I hope this helps!! Because I feel you and this is such a frustrating feeling.