As an outdoor runner, I’ve slogged through this endless winter, donning a hat and gloves on days when I should have been celebrating spring. Luckily, I’ve had some serious motivation to keep me going: the upcoming, inaugural Nike Women’s Half-Marathon in Washington DC on April 28th. It won’t be my first time at the rodeo, so to speak, as I’ve done three half-marathons before. But having never trained with much of a goal beyond finishing those 13.1 miles—and let’s be honest, that will ALWAYS be my ultimate goal—I chatted with Marie Purvis, a trainer who developed the Nike Training Club’s program, to see if I could up my game. Here, some of Purvis’ top tips for achieving a personal record and just making the process less painful.

Gisele in W's August 2008 issue.

Don’t forget about your back:
Purvis has her clients weight train about twice a week. And while her prescription hits the areas you’d expect—stabilizer and lateral muscles in the lower body, glutes—she also recommends focusing on the torso. “I do a lot of back work,” she says. “People’s posture is really poor, in general. And if your posture is poor, your running form is going to be poor.”

No one’s grading you, but think bell curve:
Many training programs encourage building up distance, with the longest run a week or two before race day. Not Purvis. “I always do a bell curve. You start at a low point, you work your way up to that pinnacle mileage—two 13 or 15 mile runs, two weekends in a row—and then taper down,” she says. “You know your body can sustain the miles but you’re able to fully recover by race day.”

Mix up your surfaces:
“The best thing is to run on a dirt trail sometimes. And I recommend doing speed work on a track instead of a road because people land harder on their feet when they’re increasing their speed, so it’s nice to have that extra cushion,” says Purvis. “Get your long runs in on the asphalt because that’s what you’re going to be racing on.”

Hills are always good:
“Even if the course is flat, you’re going to be a much stronger runner from running hills,” says Purvis. “Hill training is interval training. You’re strengthening and then building endurance under a lot of tension.”

Forget the bottomless pasta bowl dinner:
“That whole carb-loading thing is a total old wives’ tale,” says Purvis. “The best meal is 40% lean protein; 30% complex carbohydrates, so not pasta, but quinoa, brown rice or a sweet potato; 10% fat; and 20% veggies.” Purvis’ preferred meal is grilled chicken, sliced avocado, a whole sweet potato sans toppings and steamed veggies.

No need to go crazy on the GU Energy gels:
“For a half-marathon, you want to plan on getting through the whole race without snacks. You should be able to get everything you need to fuel you in your morning breakfast,” says Purvis. She does caution that it depends on how long you’re running: “If you’re two hours and fifteen minutes or longer, you definitely need GU.”

Try to refuel post-race, even though you’ll feel more like hurling (my personal experience):
“As soon as you cross the finish line, drink some water. You’re not going to be hungry, but if you can force yourself to eat a banana, that’s great. It will prevent any headaches and the sugars and carbs will be absorbed really quickly,” says Purvis. “If you can eat a full, high protein meal within an hour of finishing, you’re going to feel like a million bucks.”

Photographed by Mert Alas and Marcus Piggott. Styled by Alex White.

I am not terminally unhappy with my figure. Sure, I have those mornings like anyone else where every body part seems to have bloated out to Michelin man proportions. But my general outlook is one of acceptance and, sometimes, even confidence. Well, enter the spring 2013 collections—with their almost unilateral focus on the bare midriff—and any claims to corporeal contentment evaporated. Whether it was Balenciaga’s skirt, jacket and bra combo or the lower rib cage-revealing look at Rochas, these ensembles left no room for error.

Vanessa Lawrence after her sessions with trainer Marc Gordon.

Intent on getting myself in shape in time to sport one of these looks to a New York Fashion Week party, I turned to trainer Marc Gordon, whose clients include chiseled models like Joan Smalls. My deadline was two and a half weeks—ridiculous, I admit.

I should preface this by saying that I was no workout neophyte: I run five to six times a week and take at least one Core Fusion class a week at Exhale. But even that regimen does not a perfect abdomen make. As Gordon intoned during almost every one of our fifteen sessions, “You can run a country mile and not have the body you want.”

Two looks from May's Ab Fab story. Click here to see the slideshow.

This became very evident as I submitted to his interval and strength training-based program. A cardio junkie—apparently it’s a common addiction among women—I had the fitness level to push through the heart-pumping jumping jacks with twelve-pound medicine balls, but I could barely manage three reps of most of his abdominal exercises. Bicycles on a Bosu balance disk? Disastrous. Planks with toe lifts on a Swiss ball? Flat out failure. Walking lunges? I thought I could do them correctly. I thought wrong.

“To change your body, you have to find all the weaknesses and ask them questions,” said Gordon, those questions being his excruciating creations. “And part of my system is cutting to the point. Get it done and get out.”

Yes, as he made clear, “the gym is the glamorous part.” Nutrition is paramount to seeing any results. I kept food sheets for Gordon and consulted nutritionist Ashley Koff RD, who considering my looming deadline, instructed eliminating sugar, processed flour, sodium and alcohol. Immediately. I was also supposed to add a green juice every day, limit dairy and avoid carbs in the evening. Two days prior to my unveiling, she recommended switching to purees and liquids only. That wasn’t happening, but I did my best.

As my chosen event—a Marni fragrance launch party—loomed, my resolve began to fail. I was spending five hours a week with Gordon (each session preceded by an extra 30 minutes of cardio), running 9 miles on Sundays and canceling plans with friends left and right because I was too exhausted and I couldn’t really drink or eat, anyway. By that final, snow-dappled evening, I was rather shocked by how confident I felt in my striped, cropped Michael Kors sweater and matching pleated skirt: my waist curved in where before it had been straight; I had actual definition, and Gordon had done a number on my previously meek posture.

I enjoyed my newfound core for about two weeks before it disappeared into an oblivion of wine-filled girls’ dinners and, yes, a bowl or two of pasta. I didn’t mourn its departure. After all, I can still run a country mile or two. And sometimes that’s enough.

For those interested in training with Marc Gordon, he can be reached at marcgordonfitness@gmail.com

Photos: Lawrence: Adam Katz Sinding; Ab Fab: Craig McDean.

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SoulCycle, New York's burgeoning network of high-end indoor-cycling studios, is finally rolling to the West Coast next month. In addition to its signature heart-pumping 45-minute indoor-cycling classes, West Hollywood exercise fiends can also try out SoulBands--the cycling-meets-resistance-bands workout that has made regulars of Katie Holmes, Tory Burch, and a bevy of toned Victoria's Secret models in New York. Expect five more studios throughout the Golden State by mid-2013 (soul-cycle.com).