YOUR BEST FRIEND CAN HIT THE BARRE and look long and lean, while your boss swears she was born to run. Haven't figured out your winning formula yet? Neither have we. So MC teamed up with FITiST — the online service that creates and schedules custom exercise routines — to help four of our editors reach their personal body goals. Here, the sweat sessions and diet tweaks that will truly deliver results and why. And if you've got similar goals, we've got the DIY moves to keep you inspired at home and on the go.

1) The Cardio Junkie: "I need to exercise close to home or the office."

NAME: Lauren Williams, 26, editorial assistant

GOAL: Tone up everywhere, especially her waist.

CURRENT ROUTINE: Runs a three-mile course outside three times a week before heading to work. "I need to exercise close to home or the office," says Williams.

FITIST FORMULA: Four classes per week

- Two 60-minute core or Pilates classes, such as the Nalini Method, a combo of Pilates, yoga, and barre. (At home, train with Nalini creator Rupa Mehta's podcasts, $60 for eight; nalinimethod.com.)

- One 45-minute Flywheel Spin class. (DIY: Jump on a bike at the gym and race the person next to you.)

- One 60-minute cross-training class like Brooklyn Bridge Boot Camp. (Brooklyn Bridge Boot Camp: The Workout DVD, $25; brooklynbridgebootcamp.com.)

WHY IT WORKS: "A boot-camp class that combines upper- and lower-body moves--like walking lunges and push-ups--gets the heart rate up quickly, burning fat and calories and toning muscles in a time-efficient way," says David Kirsch, a personal trainer in New York City who works with Anne Hathaway and Kerry Washington. Turning up the resistance on a bike, in combination with sprints, will rev calorie burn and tighten the core, challenging her muscles more than her slow and steady jogs. For a flat belly, "she needs to target the muscles that run down the front and sides of the body as well as the lower back," says Kirsch. Translation: If she opts for a run or cycle session, she needs to squeeze in a 15-minute ab class first or do planks instead of hitting the couch at night.

NUTRITION EXTRA

DIET DERAILER: "I snack a lot and have several glasses of white wine most nights--I probably eat about 2,800 calories a day," says Williams. (Approximately 2,000 calories are recommended for the average 135-pound woman to maintain weight.)

SMART SUBSTITUTE: "Eat breakfast to prevent starving by mid-morning," says Sharon Richter, a registered dietician in New York City. She recommends a whole wheat English muffin with two scrambled eggs or whole grain cereal with plain, low-fat almond milk. "Plan snacks ahead of time and switch to red wine; it contains good-for-you resveratrol." Richter says.

2) The Newbie Mom: "I used to be a runner, but now I have no time."

NAME: Sophia Banay Moura, 31, features editor

GOAL: Shed the last 5 post-pregnancy pounds.

CURRENT ROUTINE: Hits the treadmill three times a week for four to five miles. "I used to be a runner, but now I have no time," says Moura.

FITIST FORMULA: Three classes per week, plus one or two runs per week

- Two 60-minute cross-training performance classes such as Barry's Bootcamp. (At home, try Barry's Bootcamp 5 Day Academy DVDs, $40 for set; barrysbootcamp.com.)

- One 60-minute core-centric class like Core Pilates NYC Core 30/30. (Also try Ramona Braganza 3-2-1 Baby Bulge Be Gone 12-Week Postnatal Workout Plan DVD, $57; ramonabraganza.com.)

- One or two treadmill runs for 40 to 60 minutes, doing intervals with pace and incline. Try 30-second sprints followed by 60 seconds at normal speed.

WHY IT WORKS: A combination of multi-platform workouts targets the stomach and hips--the areas where most post-pregnancy weight lingers. "She might look at her belly and think she needs to lose 5 pounds, but it's more about regaining muscle tone," says Ramona Braganza, a personal trainer in Los Angeles who keeps Jessica Alba and Halle Berry in shape. "Just because something used to work for her--like running--doesn't mean it's always going to work, especially after a major life and body change."

NUTRITION EXTRA

DIET DERAILER: A daily late-night ice cream habit. "I can't end the evening without it--and have a full bowl every time," she says. Plus, the weekend is a food and drink free-for-all. "I have several cocktails on Saturday nights and enjoy a big brunch--with fries!--and pasta with Bolognese sauce on Sundays."

SMART SUBSTITUTE: "Rice-based, non-dairy 'ice cream' or fruit sorbet will let her keep her nighttime ritual but has way less fat and sugar," says Oz Garcia, a nutritionist in New York City. Try Rice Dream Cocoa Marble Fudge Frozen Dessert (tastethedream.com). And ditch the junky carbs with fat, like french fries or pasta with meat sauce. "Having heavy carbs every three days can cause dramatic weight gain--make it once a week max," advises Garcia. Try pasta made from quinoa, corn, or rice to minimize bloating.

3) The Foodie: "I'm pretty motivated to exercise, but I always eat out."

NAME: Ying Chu, 35, beauty and health director

GOAL: Burn fat and build muscle without bulking up. "I'm pretty motivated to exercise, but I always eat out," says Chu. "Plus I travel often, so I need a routine that works on the road."

CURRENT ROUTINE: Runs three miles or takes Spin class three times a week; adds a Vinyasa yoga or strength-training class a few times a month. "I'd love to fit in four to five morning sessions every week."

FITIST FORMULA: Four classes, plus one run per week

- Two 60-minute cross-training performance classes like AS ONE, a circuit-training class that blends jump squats, pull-ups, a stair-climber, and stationary bike. (At home, try Amy Dixon Breathless Body 2: The Edge DVD, $20; amydixonfitness.com.)

- One 60-minute core-focused class like 60-minute Real Pilates. (DIY: Real Pilates creator Alycea Ungaro's 15 Minute Everyday Pilates apps, $7 each; realpilatesnyc.com)

- One 60-minute yoga class such as SLT (Strengthen, Lengthen, Tone) yoga. (Also try Kristin McGee Strong, Sexy + Svelte DVD, $17; kristinmcgee.com.)

- One 35- to 45-minute run per week.

WHY IT WORKS: "The muscle-confusion aspect of this plan--having so many different kinds of workouts--will help make it easier to fit exercising into her hectic lifestyle," says Kirsch, who recommends Chu try his Look Fit: 5-Minute Quickies routines on YouTube when she's traveling.

NUTRITION EXTRA

DIET DERAILER: Healthy salads at lunch turn into anything-goes for dinner.

SMART SUBSTITUTE: "Scope out the restaurant's menu beforehand," says Garcia. "That way, she can map the week's meals." At dinner, choose low-fat, low-carb dishes--such as beef carpaccio over arugula. "The rule for eating out is no carbs," says Garcia.

4) The Multitasker: "I'd like to start exercising four times a week—but need to keep it quick."

NAME: Lea Goldman, 36, features and special projects director

GOAL: Drop 10 pounds; gain energy.

CURRENT ROUTINE: A 60-minute boot-camp-style class once a week and, occasionally, 20 minutes with a strength-training DVD in the living room before getting her son to preschool. "I'd like to start exercising four times a week--but need to keep it quick," says Goldman.

FITIST FORMULA: Four classes per week

- Two 30-minute boxing classes like the ones offered at Aerospace. (At home, work out with Aerospace cofounder Michael Olajide Jr.'s AeroBOX System of Sleek DVD, $60; aerospacenyc.com.)

- One 45-minute Flywheel Spin class. (Also try a workout that mimics the same heart-rate racing effect without the bike, like the Exhale Core Fusion Cardio: Pure Intensity DVD, $17; acacialifestyle.com.)

- One 60-minute Pilates ProWorks reformer class. (DIY: Gaiam Pilates Abs Workout DVD, $15; gaiam.com.)

WHY IT WORKS: "She needs to burn about 3,500 calories to lose 1 pound, so she'll have to pack in more calorie-zapping workouts to lose about 5 pounds a month. With what she's doing now, she's probably only reaching around 800 calories per week," says Braganza. Boxing hits the perfect mix of high metabolic conditioning and muscle defining in a short amount of time, continues Braganza. And cycling skyrockets calorie burn and tones leg muscles, which helps scorch calories even at rest. "Pilates concen-trates on cinching in the waist," says McGee.

NUTRITION EXTRA

DIET DERAILER: Post-lunch sugar. "I have a major sweet tooth," says Goldman.

SMART SUBSTITUTE: "Eat a more satiating lunch so that she doesn't compensate with sugary snacks," says Richter. At lunchtime, add healthy fats like avocado to a salad.

Go to www.fitist.com this month to sign up for the MC editor workout plans you see here.

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