Maybe sign up for a remote learning course, learn a language that kind of thing?
To be honest though, if I needed to just kill time I’d either sign up to Netflix and catch up with all the highly-rated telly I’ve missed or do what I did last time I have a broken leg, get a games console.
May I suggest a PS4 or XBOX and the Witcher 3 + expansions, seriously seriously good, brilliant story telling and actually very good value entertainment on an hourly basis.
The trouble with recreational drugs is they can become a lifestyle that’s hard to snap out of. But if that’s what you need to stop you crawling up the walls, so be it, I can’t judge, not in your shoes.