St. Tropez is known for many things—Brigitte Bardot, four-hour lunches at Le Club 55, pétanque on the Place des Lices—but its proudest creation may well be a thick slab of pastry cream sandwiched between two domes of sweet brioche and sprinkled liberally with sugar. The lush tarte tropézienne is all over the place, and yet, during the month I recently spent in the town, I never once saw someone eat it. Local lore has it that a pastry chef served it on the set of …And God Created Woman, prompting Bardot herself to christen it the tarte de St. Tropez. It’s a delicious image, the two of them together, voluptuous, bouncy, and tempting.

In a place with its own brand of pastry and celebrated suntan—you know the lyrics, “Bain de Soleil, for the St. Tropez tan”—wellness may not be the first thing that springs to mind. But if you navigate it just so, dodging the sprays of Ruinart, St. Tropez could almost be considered a spa town. Not in the Austrian tradition of chewing raw beets 30 times at every meal. Please. We’re talking the South of France, where wine and cheese are essential to civilization.

Step one to the spa life is picking your moment. That means avoiding July and August, and possibly late June. St. Tropez is pure debauchery in high summer, with boats clogging the harbor, influencers crowding the Dior boutique, and restaurant D.J.’s pumping out E.D.M. as you consume your Wagyu beef tartare topped with truffles, caviar, and gold leaf. If you’re that person, enjoy. If not, turn around and head for the hills.

Step one to the spa life is picking your moment.

That’s step two: hightail it out of town to an oasis perched over Gigaro Beach called Lily of the Valley. It’s a place that encourages calm, movement, and balance. Balance, you might ask, eyebrow raised? You couldn’t be farther from Les Caves du Roy.

With its tobacco-colored wood, abundant potted plants, and expansive views of the sea and hills, the resort feels a bit more like Northern California than southern France. Philippe Starck designed it with an airy, deeply comfortable, and almost rustic ease.

My visit started with a baptism by fire called Bioimpedance Analysis. I stood, eyes closed, on what looked like a bathroom scale while small electric currents calculated my fat and lean muscle mass, along with my biological age. Fun! I told the technician to kindly keep any bad news to herself. “But, madame, the numbers are good!” she replied. Disaster averted, I headed to the well-equipped gym for an elliptical, weight-lifting, TRX workout as I gazed at the bronzed bodies by the pool.

Lily of the Valley offers adventurous outdoor workouts, too, including sea wading—a kind of power walking in the Mediterranean—mountain biking, paddleboarding, and something called Crazy Stairs, which involves interval training on six steep flights.

After all that exertion, you may feel as if a massage is the only appropriate response. The one I had started with dry brushing and finished with luxurious strokes that presumably gave my lymphatic system some T.L.C. The French are zealots about lymphatic drainage, and who am I to argue?

This being the South of France, you can also do absolutely nothing. Go right ahead and flop your unanalyzed body on a chaise longue on the peaceful beach. Raise a glass of rosé to your lips and feel free to call it weight lifting. The hotel’s Italian Brigantine restaurant, overlooking the glistening Med, delivers pasta and wood-fired pizza to the carefree, and grilled fish with olives and tomatoes to the careworn (me). No complaints, though, because I loved it, as did my biological age.

I should explain that I was sampling the Shape Club weight-loss program, which, according to the consulting nutritionist Jacques Fricker, “doesn’t involve depriving yourself of the foods you enjoy … to avoid frustration.” The waiter at dinner told me sweetly that he was forbidden to serve me a cocktail and handed me a list of dishes designed by chef Vincent Maillard, who trained with Alain Ducasse. That night’s offering was a fragrant and enormously pleasant vegetable stew with black truffles. I ate it happily, even while my partner oohed and aahed over his grilled scallops with a bump of caviar, filet de boeuf flambéed with cognac, glasses of wine, and a creamy chocolate-dessert concoction. I wasn’t frustrated in the least.

If you choose to sprinkle your wellness with mild hedonism, there are other clever places to indulge both. La Réserve, a hotel high in the hills of Ramatuelle, has an anxiety-reducing view of the sea and a hushed sense of luxury throughout. I signed up for the Rejuvenating Dream Day, a name that turned out to be remarkably accurate. There was lunch by the pool—sea bass with capers, roasted tomatoes, and a shower of chervil—served with the gentlest breeze. My spa treatment started in a tub equipped with jets and filled with marine water and essential oils, and included a body scrub and a “better-aging massage,” which aimed to improve my circulation, prevent tension, and stimulate the oxygenation of the skin. If I’m going to age, I might as well do it better.

Cheval Blanc, an opulent retreat with a Guerlain spa, is just outside the bustle of St. Tropez. Its small private beach has perfect sand that’s groomed more lovingly than Nicole Kidman’s extensions. The hotel’s gym opens to a sunny courtyard, and non-guests can pay a membership fee to sweat like a biohacking billionaire. The nearby spa is both large and discreet, with a long list of treatments and a custom-made soundtrack that’s meant to capture the spirit of St. Tropez. Strangely, I get it. There are Louis Vuitton blankets on the massage beds and Guerlain products on your epidermis. And guess what? My lymphatic system was, once again, drained like a champ.

I had lunch on the terrace at the Michelin-starred restaurant looking out at the bay. And when it started to rain, the servers maneuvered the umbrellas so gracefully that I didn’t feel a drop. La Vague d’Or, the hotel’s main restaurant under chef Arnaud Donckele has three Michelin stars. He also oversees the more low-key lunch, if you can call lobster ravioli in an intense lobster broth and shrimp carpaccio low-key.

With coffee came mini tartes tropéziennes, and I popped one in my mouth feeling not like Bardot—I’m not delusional—but as if, at last, I’d had the full St. Tropez experience.

Linda Wells is the Editor at Air Mail Look