Learn new skills. Through volunteer work you'll make new friends. If you're not the social type, that's fine, too. There are many opportunities to work alone and still help others. You do not have to volunteer full time.
Many places ask no more than an hour or two weekly.
Believe me, when you sacrifice one or two hours of TV reruns you won't miss a thing. It is terribly hard to function when you're sick. If you have any time when you're feeling well at all, it's worth mustering the strength to volunteer. I don't want to be with other people. It matters not whether you're outgoing or introverted.