Susan Johnson was never afraid to talk about death. But whenever she tried to discuss her end-of-life wishes with her children, both in their 40s, they deflected the topic with jokes. And her primary care doctor never raised the issue.

Then, a few years ago, a surgical complication left Johnson hospitalized for months. She felt death close by, and it scared her. When she recovered and returned home to Salem, N.H., she invited her son and daughter for an Italian dinner, followed by a mandatory conversation — one with no jokes allowed.