If you’re one of those people reading this in the latest edition of a dead-tree product called a “magazine,” you’re probably sufficiently retrospectively oriented to know what I’m talking about when I say, age is not just a number. It’s more of a . . . I don’t know, a dull, ever-present throbbing in the left knee? A strong sense that it’s time to call it a day by 3:30 p.m.? A score on the cholesterol chart that actually makes a loud dinging noise when you open the email? (It typically comes attached to an angry-sounding demand for a follow-up discussion with the doc, a medical version of finding “See me after class!!” written on your dismal seventh-grade term paper.)

Last month I observed a milestone: I reached the age of “buying a book on aging at Costco.” I perused the first half carefully, then found it made an excellent coaster under my wineglass. It was not what I thought I was getting.

The book is by Sanjay Gupta, who, despite being on CNN, actually knows what he’s talking about, in his case brain surgery. From sawing open people’s skulls he segued into being a televisual health and wellness coach for the kinds of people who buy books at Costco. Remember when brain surgery was a more celebrated skill than being perky on television? I guess on CNN you don’t have to win a fight with Medicare and Aetna every time you want to pay the mortgage. Gupta’s latest is called “Keep Sharp: Build a Better Brain at Any Age,” and I bought it mainly because I heard it tells you to brush your teeth left-handed. What a fascinating life hack! I thought. Surely the book was bursting with similar tips. I was very excited when I got to that portion of the text — a throwaway sentence noting that doing unfamiliar things can shore up neural pathways.

So I got right to work on building a better brain, but it turned out that I couldn’t, actually, brush my teeth left-handed. It’s surprisingly hard. I had to switch mitts halfway through, or I would have been standing over the sink for an hour. Three weeks later, I’m getting pretty good at it, though I still find that my right paw unconsciously clenches up during the process, as though disbelieving about its sudden second-best status. Given the degree of difficulty, I suppose my plan to learn to play the piano in middle age is unlikely to lead to much of anything.

That the sinister manus method of oral care takes my full mental concentration is, however, reassuring; it makes me think I am giving my neurons a nice little jog around the block. Gupta has some other sound ideas also, for instance when he proposes that the brain is a use-it-or-lose-it organ, hence quitting your life’s work at 65 to watch CBS procedurals every night could accelerate aging. No problem there; I have no intention of retiring because I figure I’m going to be paying for my kids’ college until I’m 110. Gupta also advises his readers to get enough sleep, by which he means at least seven hours a night. Seven hours! If you factor in weekend snoozathons I’m averaging well over eight. Sleeping is an achievement of which my mastery is complete.

But Gupta’s book is otherwise largely a bust: The doctor’s central point is that mental and physical wellness are inextricably linked. Alzheimer’s, for instance, is much less likely to strike the physically robust. Something to do with blood sugar turning to cement if you sit around too long. If this book could be distilled into one directive, it would be: Exercise or crumble. Gupta has a lot of physical-fitness schemes to discuss, all of which are no doubt useful, but he never quite grasps the central failing of his argument, which is: Who wants to exercise? Keep Sharp is a bait-and-switch that promises that you can limber up your mind by performing fanatical amounts of physical exertion every damned day of your life. Take a break from writing, this guy tells me, and walk up and down the stairs for ten minutes each hour. It’s easy!

No, it’s not. Moving around takes effort, and why would I do that when there are comfortable chairs everywhere? I learned from Gupta that I’d be a happier, healthier, age-resistant machine if I started running triathlons (as he does, the bastard). If the book had been entitled “You Should Run Triathlons,” though, I wouldn’t have bothered. I don’t even want to be an athlete, much less a triathlete. Gupta even does 100 push-ups a day. And he does look good, doesn’t he? We should all be so youthful at 52. But, again, 100 push-ups is exhausting. Couldn’t I just take a pill or something? I came to this book looking for a simple program of trickery that would make age bypass me and go rattle the next guy instead. What I got was a paean to gym rats. Gupta notes, quoting “my friend Matthew McConaughey” (egad), that it’s important to break a sweat every day. How am I supposed to do that from this desk? These takes don’t write themselves, and no one is going to pay me to do crunches.

What I really need in my life is not Dr. Sanjay Gupta but a nice, straightforward quack who will tell me that I’ll age twelve hours in reverse for every hundred grams of beef jerky I put away. Give me more shortcuts and fewer demands that I become a superhuman fitness machine. What Gupta is up to is exhorting me to be a (much) better person. Why start now?