I've found that for exams, mixing it up is the best way to stay attentive. Depending on the length (especially if it's a really long multiple choice–think SAT or something along those lines), I like to do a few problems then flip to the back of the book and work problems from there. When I feel my focus lapsing, I go back to the beginning and pick up where I left off.

I've found that this strategy works elsewhere as well. Simply mixing up my environment (working in a coffee shop vs a library vs my room vs etc) tends to make me focus better as I adapt really well to new situations but grow complacent in routines.

As for the social side, I've found that forcibly inserting myself into situations I might find uncomfortable is the way to go. I tended to group up with people who are trying a similar thing and we ended up forming a close bond, because I (and others like me) prefer fewer, closer relationships.

For example, I joined a Discord server someone made for my dorm. On the first day, someone offered to play cards with people and I went even though I would maybe normally stay in. About half the people there are in my friend group now.

Hopefully this rambling helps you :)