You have turned up for your annual medical checkup. The doctor has taken your blood pressure, inquired about your diet and exercise patterns, and asked whether you smoke. Then come some rather pointed questions about your social life: Do you have many friends? Do you socialize? Which groups do you belong to? How diverse are they? How important are these groups to you?
Even though these questions are unexpected, you go through the long list of your active memberships: your book club, volleyball team, hiking group, work colleagues, and so on. Your doctor congratulates you and says that you are doing exactly the right things. You even learn that because you belong to so many social groups you should not worry if you skip your gym visit every now and then.