IMO with any language one needs some sort of motivation that's media based, as just trying to go through courses is extremely tedious. It's the same for Korean, Japanese, German and just about every other language I've studied/dabbled in. I didn't find studying kanji particularly difficult, it's just some tedious work required upfront to get to the actual goal: communicating.
So for languages I would recommend pursuing native media and language exchanges. Discord servers are great for this as you can find native speakers and people to answer grammar questions, etc. For me, watching Korean variety shows motivates me to study vocabulary, and exchanges are great for making friends to commiserate with.
YMMV but actually being able to play music really deepened my connection with music. I understand and appreciate certain things now that would have been hard or impossible before.
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It's dawned on me just now that basically most of my hobbies have a social element to them. So it's not just limiting my computer time, but also getting me to go outside and make new friends. Having social groups that aren't just tech nerds is quite nice as well.
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Those are just some example hobbies, anyways. I'm sure there's a hobby for you.