One thing is to keep involved with people.
My mother in law is 87 and still volunteering. She spends two days, at least, with the Shepherd Center which is a national organization. This is an organization for seniors to help seniors and learning opportunities.
The mission is to help elderly seniors remain relatively independent. When you need a ride to a doctor or hospital or shopping, and do need a ride, they have volunteers who will provide a ride. There are limits - once a week, but for the older volunteer it is a means to stay involved, help others, and socialize.
Adventures in Learning are classes on a myriad of subjects - dance, history, politics, sewing, music, and many more.