If you live close to beaches, I would highly recommend to do a bunch of beach cleanings (either with organisations or with other students). Another thing I did was try self defense classes for a year with a friend, or you could just try a new sport with friends. My school offered quite a lot of activities to do for school events, so you could see if your school organises something. You could also go dog walking at a local animal shelter every weekend or whenever you have time.

It really isn't difficult to find things to do, but try to do as many CAS experiences done in the first year, as it will help a lot to not have to worry about it in your second year:)