From your example you could just be introverted or just not interested in what people around you are interested in.
Something important to answer is, why are they the “things you should be doing”? If it’s because people tell you to, and you want to be included but you don’t have any interest in the activities, that’s normal, don’t feel like you need to be more social than you want to be. If they’re things you want to do, but you can’t find the energy or focus to do them, it could be ADHD, depression, or something else.
I’d say schedule a physical with your doctor, have them check blood work and see if you’re getting the right nutrients, and if that all looks relatively fine, talk to a therapist. All of that is good to do regardless.
It could also be technology training your brain to have a short attention span. Go do things that interest you that don’t involve screens. Could be as simple as going on more walks, learning a new skill, anything that doesn’t involve consuming entertainment (Lemmy counts as entertainment).