Want to Fly Like a Circus Artist or Balance Like a Surfer? Beat Boredom With Fantasy Fitness

At Equinox Fitness in Manhattan, patrons work out in a Jukari class. Designed by Cirque de Soleil, the class employs trapezes hung from the ceiling.

I have a rich exercise fantasy life; while running, I like to pretend I'm leading the New York City Marathon, and on the bike I imagine the bunny hill in my local park is really the biggest climb of the Tour de France. Hey, whatever gets me out there. And that's the point: Exercise should be fun, and matching your workout to your daydreams of being a pro quarterback or a member of the cast of A Chorus Line is a great way to do that. (The fun factor is important because boredom is one of the most common excuses for not exercising.) The good news is that even some of the more extreme training regimes have been tamed in classes for mere mortals. Suppose you want to . . .

Train as if it's your job to be fit. For firefighters and members of the military, being out of shape obviously has far greater consequences than not fitting into last summer's bikini. No wonder many of them flock to CrossFit, a strength and conditioning program aimed at improving general fitness. (As the company says, "Our specialty is not specializing.") Using equipment ranging from standard barbells to gymnastic rings and your own body weight, CrossFit classes teach you basic form and skills and then guide you through classes that include the "Workout of the Day," an ever changing, intense, and frankly often intimidating-appearing set of exercises, which may be short and brutal or longer and at a slightly easier pace, depending on the day. Indeed, CrossFit has a reputation as being for only the superfit. But all of the workouts can be modified even for folks who aren't particularly in shape, says David Osorio, head coach and owner of CrossFit South Brooklyn, where I took a class.

Our main workout, for example, was five dead lifts using a barbell followed by 10 "burpees" (squat, kick out your legs, do a pushup, come back to the squat, and leap as high as possible). Five times. As fast as you can. And there were a few people who whizzed their way through it (one guy finished when I was still in the middle of my third repeat). But plenty of others used much lighter weight and took it slow. Everyone finished, and the faster folks cheered for, rather than sneered at, us. Affiliates have leeway to develop their own programs and may attract different crowds depending on the location, so find one that feels right to you and has other beginners if you're not a pretty regular exerciser. If you're already an expert and don't want to take a class, you can get the workouts directly from crossfit.com and follow them on your own.

Dance like Debbie Allen. Typically, the choreography at aerobics classes that focus on dance moves is more Jane Fonda than Bob Fosse. But a growing number of classes at gyms and health clubs make you feel like a true dance student, without requiring that you already have technique. At Crunch Fitness's new "Fame" class, some participants wore old sweatpants and others looked as if they were headed to a Broadway audition—but everyone seemed to be having a good time. The workout is structured like a jazz dance class, with a warm-up, turns and movements across the floor, and learning a short routine before "performing" it for one another in groups. The nod to Fame came in the music—which included songs from both the original movie and the recent remake—and the choreography, which the instructor said was taken from the new movie and was doable for people with even a modicum of rhythm.

Do a ballerina's pliés. If your goal is less to shake your stuff and more to get the long, lean shape of a classical dancer, Physique 57, based in part on the dance-focused Lotte Berk Method—may be for you. In a studio with a barre, we did a series of isometric exercises and stretches using a few pieces of equipment, but mostly our body weight, via leg lifts, knee bends, and the like. Even if you're used to lifting heavy weights in the gym, what the company's website calls "Interval Overload" and I call "so many repetitions of a leg lift that I was begging for the end," is challenging—but not impossible. Just when I thought I couldn't take any more pulses, we'd retreat to the floor for some stretches. It may take a while to get used to the proper alignment for the exercises, but there are classes aimed specifically at beginners, and my instructor was careful to correct improper technique. Classes are available only in New York, but you can get the workout on DVD, available at physique57.com.