A 45-Year-Old Man Walks Into a Gym...
Credit: Photograph by Michael Edwards

My new life is regimented but manageable. There is more restraint, less frivolity, and plenty of the sprouted-grain bread that evokes Boulder in the 1970s. My diet has been stripped of hot-fudge sundaes, Tuesday-night gimlets, and sides of bacon. Three weeks into the new regime, I open the fridge, scanning the shelves for some blueberries, some leftover cod, or a swallow of white wine, when I discover a trio of tall, shiny cans of my favorite beer standing neglected behind the almond milk. How long had I left them just standing there? I can't even remember the last time I had fries. I've become one of those people who eat those coarse, whole-grain crackers that resemble, with depressing accuracy, corrugated cardboard. I smear them with natural peanut butter, pile them high with tuna and tapenade, anything to bring flavor to the packing material that now somehow qualifies as a snack.

Thankfully, I've not had to count calories or weigh my food. I don't have a diet to follow. As it turns out, eating the things you're pretty sure you're supposed to eat and not eating the things you're pretty sure you're not supposed to eat is the diet. Another way to put it: I start thinking of flour as sugar and try to cut way down on sugar.

The one surprise involves breakfast. Joy Pape, a nutritionist recommended by the Cornell Weill Center, tosses out the zero-fat Greek yogurt (what I thought was a virtuous breakfast) because it lacks protein. She suggests an actual protein shake, which I come to love even if it's texturally impotent, lacking crunch, crust, and brown-sugar topping. I have a fairly sensible, wheat-free lunch most days. Dinner varies, but I try to eat a lot of fish, nothing more than a reasonable amount of starch, and lots of vegetables. I might have a cookie or some fruit for dessert, but I'm not standing in the pantry with an open bag of chocolate-chunk cookies, wolfing indiscriminately. The Greek yogurt I used to eat for breakfast has been elevated to "treat" status. I top it with blueberries and a paltry amount of homemade granola and call it dessert, that thing you eat before you fall asleep to the sound of your rumbling stomach.

My primary dietary weapon is the awareness that I now bring to everything I consume, particularly anything that includes bitters or cocktail onions. Even wine is suspect. The era of the bottomless glass of riesling is apparently over. For what must be the first time, I am conscious of the calories in every blessed, sweaty glass. I learned how to not get terribly plastered years ago, but now I was drinking for my health. It isn't fun or carefree or soulful in any sense, but it isn't difficult either. I get used to not having enough to drink.

After more than a month, my trainers and I are still focused on the unsexy, the functional, the invisible. This is fine by me, but it's still a blow to my inner meathead. V explains his medicine/candy philosophy: "I give some of what you want in terms of seeing results – burning fat, building muscle – while also giving you what you need." He doesn't check the size of my pecs or the definition in my arms, and when he steps back to assess me, it's my posture he's checking, and it's improving. "Pretty good," he says, poking me in the gut. "Tighten up."

So I do my lunges, my squats, my planks. Rotational stability and core competency are my twin objectives, though my posterior chain – the network of muscles that connects along the back of the body – also needs attention. V tells me it's the key to sitting up straight and engaging the rhomboids, the muscle situated between the spine and the shoulder blades, rather than pressing my shoulders into service and injuring them further. So I dutifully stick to back-opening pulls rather than pec-popping presses. When I do get my hands on some iron, I don't exactly lift it: I hold dumbbells by my side while I step on and off a bench press, or swing kettle bells to enhance my core. I hold them and do lunges and haul them up and down the gym corridor. Only occasionally do I press them overhead, but as part of a squat sequence that makes few claims on getting jacked.

When I'm not training with David or V, I do cardio: Two or three times a week, I strap on a heart rate monitor and climb on an Arc Trainer. As per their instructions, I don't hold the rail, relying on core and glute activation (what else?) to keep upright as I put myself through the paces. After a few minutes' warm-up, I do intervals [see the Cardio Project, p. 104], cranking up the level and incline for a minute on, two minutes off, all the while fiendishly gazing at the heart rate monitor on my wrist for a suitable spike. To me, this is the height of self-obsession, the exact fitness-minded myopia for which I've indicted others, and I love it. I soon become restless and dissatisfied when I don't hit 173 or higher during a workout.

In some small ways at least, I am becoming the gym type I envied and looked down upon: preoccupied with self-improvement, a little too pleased by my own progress. But it's fitness, not plastic surgery. I've earned the gains I've made, and making them isn't turning me into a preening narcissist. It's just making me stronger.

One day, I'm lying on my back between a rack of kettle bells and a bench press, squeezing a ball between my knees while V pokes me in the ass. "Tighten those glutes," he hisses as he tries to slap the ball loose. I'm gritting my teeth, intent on keeping the ball where it is, when I first spot the guy in the middle distance: a scrawny septuagenarian at the pull-up bar. Joe Lieberman in gym shorts. And I watch from the corner of my now sweat-stung eye as he hops up, gets himself comfortable, and knocks out a set of pull-ups like he's opening the trunk to his Lexus or bouncing his grandson on his knee. Just like that. Eight, 10, a dozen. I lose count. That's when I make up my mind: That guy, that skinny bastard who probably lost his virginity listening to Sinatra – I wanna be that guy.

Two months in and two days shy of my 45th birthday, I subject myself to the scale, the calipers (fat pinchers, I call them), and the numerical reality of it all. I wonder if the progress I feel I've made will be backed up with actual figures. The news is good: 186 pounds. BMI of 19 percent, down seven full percentage points. Thirteen pounds of fat.

I look at the scale, the chunky metal part settling on territory and on numbers not used to calculate my weight since the 1980s. I'd take a picture with my phone, but I'm afraid that holding it might tip me up to 187.