I was always able to get part time work at fast food places, cleaning crew for hotel/motel, cleaning crew for restaurants. If there's a factory near you, see if they are hiring seasonal workers for something - I worked a factory job once stuffing seeds in promotional literature.
For volunteering, if there is an animal shelter nearby (and you are not allergic), they are always looking for people to clean the kennels, take the dogs for walks, etc. Or go to the library and see if they are looking for volunteers to read to children - or a boys/girls outreach which may be looking for volunteers.
If you still can't find anything, then if there is something you are interested in learning, check out some books, do some research and try to learn it. Maybe take some time to go hiking or for walks every day you can. Experiment with cooking/baking new stuff (gather interesting recipes on the internet - or try the daily recipe from the PTC task - as long as it's not too exotic
)
Either that or try to start your own group for some activity you like to do - see if you can get other in the neighborhood/area to join you (maybe organize a block picnic or party to get to know your neighbors better).
Hope you find some of these ideas useful.