Old joke: How do you live to be 100? Make it to 99 and then be very, very careful.

Being, as my wife says, a cornball at heart, I told that joke, which I heard many times from my father, to Jean Murphy when I met her at the Redwoods retirement community in Mill Valley, where I was photographing her for a feature for Marin Magazine.

Jean, 99, smiled mildly at my attempt at witticism, a  smile she had no doubt developed during her many years of teaching and had reserved for those  student she considered beyond salvation. Reaching 100 is no joke for Jean, and she is hardly sitting around waiting for her odometer to hit three digits, which it will do on Dec. 2.

In the hour we spent together in her crowded, but comfortable first-floor studio, Jean told me of outings to S.F. Symphony or Berkeley Rep or a community drumming session or protesting with The Mill Valley Seniors for Peace.

A busy lady, Jean was also this year’s prom queen at The Redwoods, an honor awarded to the oldest attendee at the event. Here’s hoping Jean wears the crown again next year.