At 103 years old, I’m the ‘world’s oldest doctor’: My 3 rules for a long, happy life are so simple—I tell it to 'all my patients'

Howard Tucker died on Dec. 22, 2025 at age 103, shortly after writing this essay for CNBC Make It. It is published here with his family's permission. I spent more than 75 years practicing as a neurologist, continuing until my hospital closed in 2022. Now, at 103 — and recently named the oldest doctor ever by Guinness World Records — people often ask how I stay happy, sharp and fulfilled. I don't believe there is one magic answer. Good genes and good luck certainly can give you a head start. But over the years, I've come to believe there are a few principles that matter a great deal. These are my three non-negotiables for a long and meaningful life — they are simple, and pretty much anyone can follow them. 1. Keep your mind engaged I tell all my patients that the mind is like any other muscle in the body: If you don't use it, it weakens. My work keeps me thinking, learning and solving interesting problems. When one chapter of my medical career ended, I found another way to keep going through medical-legal review and learning how to use social media. I'm not looking for an excuse to stop. In my early 60s, I attended law school at night after working full-time as a physician. I passed the Ohio Bar Exam at 67. I never set out to break a record. I did it because law, like medicine, interests me and I have always believed it is important to keep learning. Work does not have to mean a job or career. …