Honestly I'd like to know a good answer to this question too.
When I was in my teens, I was an overachiever; I played in the state team for two different sports, played guitar and wrote songs, got near-perfect grades, and still had time for other shenanigans like skateboarding, screwing around with my friends, blogging, occasionally gaming, gettin' drunk at parties, etc. I was an avid reader too. I don't know how on earth I had time for all of it.
Now I'm 37 and I live alone and work full time. Taking care of my apartment and looking after myself (gym, cooking, shopping, etc.) barely leaves me with enough time left over for the aforementioned screwing around. I don't play guitar anymore, can't play competitive sports anymore due to injuries and stuff. When the weekends roll around I just wanna take myself out for lunch somewhere and then drink in the evenings (I really should break the drinking habit). I enjoy gaming but that too is a hobby that comes and goes for me.
I am for sure guilty of doomscrolling Reddit (now Lemmy) instead of doing more productive things, including reading books.
Others have suggested picking up an instrument. My musical tastes have evolved a lot over the last 20 years but I still listen to music like 12+ hours a day. If you're more into electronic music, maybe consider getting a cheap mixer and learning to mix/beatmatch. I say this as someone who now listens to a LOT of electronic music and bought a mixer for myself a few years ago...but still never really took the time to learn it. It would be the perfect hobby for me cause I get to listen to the music I love and be creative at the same time. But my motivation has been lacking...
Sorry this turned into a personal rant.