Charles “Hap” Fisher is pushing 103. He doesn’t hear well, he’s got a bum hip, and he needs a pacemaker to keep his ticker beating right. And yet every day he still pulls out his calculator, trying to bring new chemistry formulas into being, trying to do good in the world. “People who don’t work 10 hours a day are sissies,” he says.

One of a growing number of centenarians, he also happens to be the oldest living resident of Brandon Oaks retirement community, the oldest alumnae of Roanoke College and more than likely the oldest scholar still actively publishing research.

My profile of him, which ran in Tuesday’s paper, was essentially a trend piece. I used one very extraordinary individual to reveal one slice of an aging America, a place where the term “senior citizen” can’t begin to capture the diversity of this demographic.

As a Nieman fellow this fall, I’ll get to learn more about the age boom — how it fits into health-care reform, its impact on programs like Medicare and Social Security, and all the other personal and political challenges that present themselves when 76 million baby boomers prepare to turn 65. I’m unspeakably grateful that I’ll get to sit in on classes taught by some of the world’s greatest brains — cutting-edge Alzheimer’s researchers, health-care economists, architects and urban planners who are trying to design the retirement communities of the future.

But I doubt I’ll meet many like Hap, who reads voraciously — The Economist being his favorite publication. When he indulges in a novel, he prefers to read it in Spanish, to keep his mind sharp.

I won’t be spending time with people like Lucille “Big Mama” Blackwell, who died a week ago Friday at the age of 85 and whose obit I had the privilege of writing Sunday. The great-granddaughter of slaves, Big Mama dropped out of school in the third grade to help her parents work a white man’s tobacco farm. She never learned to read, but there was a wisdom about her that I doubt I’ll bump up against at Harvard — or anywhere else. “I have no spirit of fear, and I thank God for that,” she told me last year. “See, when it’s my turn to go, I’m ready to stand before the King and hear him say, ‘Well done, Lucille.’ ” 

I won’t be a five-minute drive from the home of Linda Rhodes, whose struggle to take care of her dementia-diseased husband, Tommy, has been the subject of some of the most heartbreaking and most rewarding reporting of my life.

These are moments you don’t get to witness every day, which is what keeps so many journalists plodding away still — despite all the industry red flags, despite the so-so pay, despite all the times we bolt upright at 3 in the morning worried about a possible layoff, or a possible mistake in the next day’s story, or how we’re going to get our kids to school and practice and music lessons — and still get that story turned in on time. 

I won’t miss the anxiety and the second-guessing you create for yourself when you’re in the middle of a complicated project — and, even though you’ve been there hundreds of times before, you’re still not sure you can pull it off again. (“You’re full as a tick with this one,” my friend Mary told me once, mid-project.)

But I will miss people like Hap, Big Mama and Linda Rhodes. No matter how complex the conversation or how heady the academic vibe, they are the teachers I want to keep foremost in my mind.