Within several weeks of being dismissed from the now defunct Lotte Berk exercise studio on the Upper East Side, Rupa Mehta began teaching classes in a rented space on West 68th Street. Sessions included a fast-paced hybrid of yoga, Pilates, resistance training, and Lotte Berk-style ballet bar stretches. Ms. Mehta decided to call her technique the Nalini Method after her India-born mother, whose first name means lotus flower in Sanskrit.

At first, Ms. Mehta would show up to a scheduled class only to find there were no students there to take it. But in the four years since she struck out on her own, her workout has won over many new mothers looking to chisel their post-pregnancy bodies, as well as other body-conscious women, and some men.

THE BASICS

The Nalini method devotes equal time to strengthening the upper body, the lower body, and the core. She caps off a series of weight-bearing exercises targeting a major muscle group with some short, deep stretches. Most movements are small, controlled, and repeated over the course of two or more minutes. Hand weights in pairs of 3, 4, and 5 pounds are used in some of the exercises, as are props including a circular resistance band, a rubber ball, a sturdy strap attached to the studio’s ballet bar, and a small, red, shield-shaped weight called a Smart Bell.

The garrulous Ms. Mehta, 28, demonstrates each exercise for the class, but does not do the workout alongside her students. Instead she moves quickly around the studio, adjusting their alignment and positioning, and encouraging them in her chirpy voice “to commit to the end of the exercise.”

“You won’t see me standing in front of the class with a microphone and a tube top,” Ms. Mehta, clad in stretch pants, a hooded sweatshirt, and a baseball cap, said in an interview.

As an instructor, she prides herself on providing personal attention, and all of the students can expect to be sweetly name-checked several times during the hour. Despite the rigor of the regimen she devised — she tells newcomers that their legs may shake, and their rear may ache during their first several sessions — Ms. Mehta said her goal is to create an environment where people of all ages, fitness levels, and walks of life feel at ease. “It’s not just Upper East Side ladies who lunch; it’s not just Upper West Side ballet dancers,” she said. “I have all types of students, from 22 to 75. It’s not about doing a split; it’s about feeling the stretch. I have a very accepting philosophy.”

Nalini students who attend classes three times a week may begin to see the sculpting effects on the upper body within a month, according to Ms. Mehta. It can take three months or more to see lower body results, such as a trimmed waist and lifted backside, she said.

THE WORKOUT

Last week, I took two mid-morning Nalini classes, each alongside a handful of exceptionally toned 30- and 40-something women, many of them mothers with young children. While my lithe classmates looked a bit intimidating, the studio, itself — filled with cushy mats, and familiar, lightweight equipment — did not.

And when the class started, most of the exercises for the upper and lower body, such as bicep curls, modified push-ups, and leg lifts, seemed relatively easy. But after several minutes of exertion, my muscles became increasingly fatigued, and finishing each exercise was a to-the-limit challenge.

By contrast, the abdominal exercises were tough from the very beginning. Just getting into the starting position — sitting down, knees bent, feet on the floor, back rounded and positioned about 45 degrees off the mat — requires more than a little strength and endurance. And the long series of pulsing and circular motions, most done while holding the six-pound Smart Bell and squeezing a rubber exercise ball wedged between the knees, upped the ante. When Ms. Mehta came around to adjust my positioning, the motions seemed even harder.

Though each exercise seemed to last an eternity — after holding my body in a plank, or a forearm-supported push-up position, for the requisite minute, I collapsed onto my mat, convinced I could not hold the position for a moment longer — the hour went by surprisingly fast. Perhaps, that’s because the equipment and the exercises vary widely, from muscle group to muscle group, and from class to class. In one session, leg-strengthening exercises were done with a resistance band; in another, students held several straight-back squats for a minute or longer. The class was exhausting, but it was never boring.

The evening after I took my first Nalini class, I went to bed fearing that mundane movements, such as walking, sitting, and climbing the subway station stairs would be excruciating the next day. When I woke up, though, there was nary a hint of the previous day’s taxing workout: My lower body was surprisingly nimble, and the soreness I felt in my arms and shoulders was imperceptible by midday.

The Nalini Method, 48 W. 68th St., between Central Park West and Columbus Avenue, 212-787-5588, groupclass$30, private lesson $125, packages available, fitness podcasts available at nalinimethod.com.