If you live in a very small city such as mine, not very much.
I always wanted to volunteer for things - but my city does not permit you to till you are 18.
I always want to go to the parks - but the parks commonly have a drug problem around here.
You could try going to the library and learn new things or go to the museum, but seeing that you are having emphasized that you cannot drive - there isn't any buses, trains, metros, taxies, or anything in reasonable walking or biking distance.