During the decade leading up to the birth of my son, I averaged 44 ounces of Diet Coke every single day, an amount equal to the volume of the original 7-Eleven Super Big Gulp cup. Forty-four ounces a day, though some days I went with BP or Mobil, anywhere with a soda fountain. Forty-four ounces a day, and that includes those days when I visited restaurants where only Pepsi was served, and sick days when I couldn’t leave bed or even swallow. In fact, when factoring in the number of “free-fills” scored at various eateries, 44 ounces is probably low-balling it.

Diet Coke was my brand. I was the college instructor who (daily) entered class with cup in hand, who built a Diet Coke policy into his syllabus, whose students commented about Diet Coke on my evaluations and on RateMyProfessor. For several years I wrote a blog called “The Diet Coke Chronicles,” wherein I detailed my odd habits, my preference for specific straw length, my argument for plastic cups over styrofoam, my ideal ice-to-soda ratio.

I was Diet Coke. The Diet Coke Guy.

Sometime in the past two years, though, 7-Eleven quietly reduced its Super Big Gulp cup size from 44 ounces to 42, and then again to 40. When it happened, I exploded in mock outrage. I threatened protests and boycotts. I threatened to shop exclusively at Circle K. (I didn’t care that much, but the outrage was expected of me. I’d written thousand-word essays on styrofoam cups, for crying out loud. If anyone should speak out about this subject, it should be me.)

Days passed, weeks, months, and my average daily consumption (ADC) dipped by about two ounces through the first six months of 2012, matching the new Super Big Gulp cup volume. And when the cup size shrank again, my ADC tumbled to 40.

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In one of my kitchen cabinets, I have (for some reason) a stack of old Super Big Gulp cups. One is absolutely blank, no 7-Eleven logo, what I call my rare “albino cup.” Another is a standard 44-ounce Super Big Gulp cup, perhaps the last original cup I saved before the stores changed from 44 ounces to 42.

And now, on occasion, I find myself using this old cup at my local 7-Eleven because the store offers a refill discount. (I save about 50 cents per transaction, which is not insubstantial when considering the totality of my annual purchases.) The clerks know it’s an older cup, and they give me winks and head-nods, as if I’ve bucked the system by not only getting a cheaper drink, but a larger drink. It should make me feel sneaky, smart.

Except now—whenever I use that old 44-ounce cup—I find myself struggling over the final 10 ounces. I find myself dumping the last of the soda. It’s a strange thing for me to do, to just call it quits and give up on the drink…I used to be the kind of guy who could drink the 64-ounce Double Gulp, who would drink warm soda just to finish it, who once (no joke) drank 13 refills during an afternoon at a sports bar watching the NCAA basketball tournament.

I’m not sure how to process this.

Am I happy because I’m consuming less Diet Coke? Certainly it’s wreaking havoc on my body (especially in heavy quantities).

Or am I sad because this feels like a metaphor for aging, like one of those comments that men my age (now in our 30s and 10 pounds heavier than in our metabolically blessed 20s, and slower, and quickly exhausted just from watching our sons spin around the room) make about our youth, like “I remember when I could eat a whole pizza by myself!”

From 44 ounces a day, to 42, to 40. And now 40 ounces is a generous estimate, as I’ll find myself going days without a Diet Coke.

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So often, we become the brands with which we identify: the bands we follow, the sports teams, the stores at which we shop. Each, we think, is a critical part of our personality, our own brand (making us, really, a collage of other brands).

For a decade, I was the Diet Coke Guy: eccentric, mainstream but not obvious, at odds with the way others would try to define my masculinity (how many “Dude, why are you drinking Diet Coke? Worried about your girlish figure?” comments have I fielded?).

Could my fading addiction be a sign that—in my 30s, with a child—I no longer have the time to care about which brands define me? That’s a nice thought.

The other day, I ran into an old friend from college. His wife is pregnant, and I warned him about the upcoming mayhem that would soon overtake his house. At one point in the conversation, he asked, “Are you still, uh…” and he motioned an invisible cup to his lips, “the Diet Coke thing?”

And I was relieved that I could say, “Yeah, you know, I do still drink Diet Coke,” but that I could say it without real passion.

Nathan Holic teaches in University of Central Florida’s Department of Writing & Rhetoric. He can be reached at Nathan.Holic@ucf.edu.