When hairstylist Martin Christopher-Harper lost 40 pounds in three months, naturally he spread the word to his friends and clients (some of the most sought-after models on the planet). The catalyst behind Harper's transformation? New York City personal trainer Kirk Myers, whose own best work is himself, having once tipped the scale at 300 pounds.

"He wanted to send this one specific girl, Jasmine to train," Myers remembers. "I was like 'cool.'" The "girl," Victoria's Secret Angel slash Fantasy Bra model Jasmine Tookes, wasn't looking to lose weight, but Myers' hyper-precise spot-training moves resonated with her.

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"The next time she arrived with Romee [Strijd], and then Romee came with her boyfriend and they really liked it," he says. "Next time Joe came, and then Joe really liked it, and they just kept coming. And then Martha [Hunt] came. Then Sara [Sampaio] came. And there was Elsa [Hosk]. Yeah, it just kept growing."

Myers' word-of-mouth following has since expanded to include 25 Victoria's Secret models (11 of whom are Angels), and a growing list of A-list celebrities. On a recent Saturday morning, Usher and Teyana Taylor warm up before their performance at Hot 97's Hot For The Holidays Show. Zac Efron, fencer Miles Chamley-Watson, and Alexis Ren are also regulars at Myers' buzzy boxing/personal training gym, which he has christened Dogpound.

The newish workout spot is not unlike other boxing gyms–with punching bags, a ring, strength-training equipment–but designer (and longtime client) Fabien Baron's influence is evident in the sleek layout and matte black details. It was Baron who changed the name from Kirk Myers Fitness to Dogpound almost a year ago. "It was just more military status," Myers says.

"We've been coming to the Dogpound for a while, even before it even opened," says Victoria's Secret Angel Josephine Skriver. "It's the first gym we've had with the opportunity to work out alone and also bring it in as a team sport. You're kind of competing with everyone around you, everybody is giving you tips. It's really motivating when you have someone else next to you."

While Dogpound, with its boldfaced clientele and slick look, might sound intimidating, it's quite the opposite. Myers' and his co-founders, brothers Dawin and Brey Pena, bring a family vibe to the fitness enclave with a tight-knit team of trainers made up of Myers' girlfriend Dara Hart, the Penas' younger brother Dennis, fitness model Bianca Vesco, and a handful of other familiar faces.

"Kirk is the heart of Dogpound. You won't find a guy that makes a gym feel more like a home. He makes the people in it feel like family right away," Skriver adds. "Together he helped us create the best workout family that all pushes each one of us to do and be our best."

Here, Myers shares some of his training tips and signature moves.

1. Throw away your scale

"For the most part, the thing is it becomes a big mind game. And your body weight can vary three to five pounds, depending on what you ate the night before, if you went to the bathroom, if you took a shower, what time of the day you weighed, what scale you used. A lot of the girls that we train started to do more weight training. Muscle weighs more than fat. So you may add weight even though you are going to look a lot better."

2. Spot-training really works

"Someone like Josephine, she likes to do weight training so she specifically likes to do legs and butt really hard with heavy weights. Jo, Jasmine, Romee, they all come really consistently so we split up their body parts," Myers explains. "One day they will do legs, next day upper body, next day they're going to do more core."

3. Add ankle weights

Myers takes donkey kicks and fire hydrants to the next level by adding resistance. "Do it with ankle weights," he suggests. "It makes it more challenging. You can also use pulses in it."

4. Don't be afraid to bulk up

"It's harder to add muscles than most women think," says Myers, who encourages his clients to build strength with heavier weights than they would normally lift.

5. Balance is key

Myers has clients do sumo squats and dead lifts on a Bosu ball. "It's a little more of an effective way to train because it forces you to activate your core," he says.

From: ELLE US