“Why is it that I remember something 75 years ago when I can’t remember what I had for breakfast?” That’s David Brown writing in his “Guide to the Good Life.” We spoke Tuesday (via phone) as we do most every week, but not as often as he and his “dearest and oldest” friend Dick Zanuck gossip, which is every day. Brown, a super-successful producer of movies, Broadway and television shows — with awards from all — celebrates his 90th birthday on July 28 at the Four Seasons in N.Y. Joining him is his wife of 47 years, Helen Gurley Brown, and his friends of 25 years, Alexandra Mayes Birnbaum and husband Byron Dobell. “There’ll be no candles.” Brown says he doesn’t want to start a fire. His recollections from “Good Life” include “hurrying home to my first wife with a $200 Christmas bonus clutched in my hands. It gave me a greater charge than the eight figure check I received as first profits from my film, ‘Jaws’.” Or, “receiving a cable from my first wife announcing her marriage — relieving me of alimony payments.”‘ But, Brown isn’t looking back. He reeled off some of his current projects – which he says keeps him young. Upcoming films include “Appointment in Sumatra” and “Peace Like a River” which he’s producing with Brad Pitt and Kit Golden. For B’way, “The Royal We,” the Mike Romanoff story and the musical “All About Us,” by Peter Viertel — based on “The Skin of Our Teeth” with music and lyrics by Kander & Ebb and Joe Stein — to bow in Westport. He also plans to produce the Billy Wilder life story, “Nobody’s Perfect.” Meanwhile, the Brown-produced “Dirty Rotten Scoundrels” continues another successful year on B’way. Brown and his book are the living proof of “The Good Life” — without tears, fears or boredom.