fun now fitness forever !



H2K Classes

Join H2K for their wide range of unique and fun fitness classes for all ages and occasions.

Kids Classes

H2K offers a variety of fun fitness classes for children! We offer everything from kids cardio kickboxing to zumba, yoga, circuit training, hip hop, play and pretend and tumbling. All of our classes are in a safe and nurturing environment. We welcome every child no matter the fitness level. We end each class with mediation and healthy goals to work on!

Summer Class Packs

Join H2K this summer for some of our super unique and fun fitness classes. The best part is that there is no commitment necessary for the summer! Purchase one of our 5, 10 or 15 class packs and use it as you go. We will be offering family and me classes, tiny kids kickboxing, kids zumba, kids obstacle course/circuit training, family mediation and more! Class packs are limited and must be used by Labor Day Weekend.

Teeny Tiny Yogis

Join us for our amazing Teeny Tiny Yogis class. This class is designed to guide your baby through yoga poses to help with body development and to help soothe the baby. Your Teeny Tiny Yogi will lie mostly on their back, stomach and in the arms of their Yogi Mommy. This class will provide an amazing bonding experience with mom and baby. Feel free to relax with other moms in our lounge after class.
Arlington Classes

Kids Yoga

Our Kids Yoga classes are fun and energetic classes, tailored to that specific age group. Students will be brought through a wide range of yoga postures while learning about the importance of breathing and the principles of yoga. Partner poses, music, yoga adventures and stress reduction are just a few things that each class offers.
Arlington Classes

Kids Cardio Kickboxing

Join us for the next level in Kids Kickboxing! Kids Cardio Kickboxing will teach your child self-defense, self-confidence, and discipline in a fun and safe environment. Kickboxing will improve their flexibility, coordination, strength, and concentration. They will learn boxing choreography, work on the bag and end each class with mediation and healthy goals.
Arlington Classes
Maynard Classes
Concord Classes

Zumba with your Toddler

Join us for our dynamic mom and toddler Zumba series. Dance around with your little Zumba star to fun and energetic music. We will play games, sing songs and have musical obstacle courses. Meet other moms while squeezing in a fun, quick workout!
Arlington Classes
Maynard Classes
Natick Classes
Concord Classes

Kids Movement Classes 4-10yrs

Kids Movement classes range from hip hop, ballet, theater movement and intro to acro! Our kids movement classes are fun, upbeat, high energy classes for young dancers or for children interested in moving in a creative and safe environment. They will work on flexibility and will be introduced to basic movements to promote agility, self-confidence, and discipline. Like many of our H2K classes we will always end class with mediation and healthy goals.
Arlington Classes

Play and Pretend Ages 1-3 yrs

An Exploration of The Performing Arts: (I.e., Dramatic Play)
This class is led by an instructor with a Master’s Degree in education with creative arts integration.
Explore the performing arts in a developmentally appropriate and fun manner! Right from birth, children are actively observing the world around them, and learning awareness of self and others. The Level 1 class balances imagination and creativity with an interdisciplinary approach to hands on, experiential, and task-based learning. Dramatic play, creative movement, music, stories, rhythm, bright visuals and manipulatives will encourage your child to gain confidence in their newfound mobility, and practice with their developing tools of communication and self-expression. Parent or Caregiver participation required.

Arlington Classes

Middle School and Teen Classes

H2K Specializes in Middle School and Teen Fitness Classes. Whether or not your child is an all-star athlete or hates working out we have the class for you. All of our classes are carefully instructed to meet all fitness levels. We always incorporate mindful activities and meditation into all of our classes to help de-stress and give your child the tools to deal with anxiety and he pressures of day to day life. Check out one of our yoga, kickboxing or circuit training classes!!

Middle School Kickboxing (11-14yrs)

Middle School Kickboxing will teach your child self-defense, self-confidence, and discipline in a fun and safe environment. They will work on circuit training, core exercises, partner drills, boxing choreography and bag work. They will also work on activities to improve their mind and body awareness. Each class will end with mediation and healthy goals.
Arlington Classes
Concord Classes

Adult Fitness Classes

Are you tired of the gym? Looking for a good class while you’re pregnant? Look no further. H2K offers a variety of unique adult fitness classes to suite your needs. We offer Ballet Tone and Stretch, Prenatal Yoga, Restorative Yoga, Curvy Yoga and more. All of our instructors are here to provide you with the best workout in the most relaxing and nurturing environment. All fitness levels are welcome.

Teen and Young Adult Kickboxing

This fun and energetic  class is designed specifically for young adults. While it is still as challenging as an adult Kickboxing class, the music is upbeat, hip and specifically selected to create a unique and dynamic atmosphere. Teens will learn self-defense, self-confidence and also learn the benefits of meditation.
Arlington Classes
Concord Classes

Teen and Young Adult Zumba

Teen Zumba Fitness Party combines fast and slow rhythms that tone and sculpt the body using an aerobic/fitness approach to achieve a unique blended balance of cardio and muscle-toning benefits. Teens are in a safe, fun environment and don’t have to worry about dancing in the same class as their moms!
Arlington Classes

Prenatal Yoga

Alleviate some of the discomforts of pregnancy and prepare for childbirth with Hatha yoga, a combination of postures, breathing, meditation and relaxation techniques. Prenatal yoga provides additional benefits for pregnant women and their babies such as increasing strength and flexibility while improving sleep and reducing stress. Prenatal yoga classes will also help you meet and bond with other pregnant women and prepare for the stress of being a new parent.
Arlington Classes

Ballet Tone and Stretch

Join us for one of our awesome combo classes. You work out while your kids work out too just in a different room. No need to drop your kiddo off at day care while you run on the treadmill. Join one of our super fun group fitness classes and give the gift of fitness to your child at the same time.
Arlington Classes

Private Classes

H2K offers private trainings, semi-private group classes and private family classes. If you feel like your child needs a little extra care, would benefit from a one on one class or just started their fitness journey this may be the option for you. Our private trainings are carefully designed for each student to optimize their abilities and provide a safe , nurturing and most importantly fun environment for them to work out in. Please check out the different training packages that we offer.

Mobile Classes

Bring H2K to your school, business, library, hospital or private event. We offer a variety of mobile classes statewide. We can tailor a class to suite your needs and schedule. Please email us for rates and availability.


H2K offers a variety of camps over school breaks and during the summer.
Check out our full range of camps


birthday packs

H2K offers super fun and healthy birthday parties for your child!!

H2K offers 3 different party packages depending on your needs

H2K Standard Party Package

$225   /   90 Mins   /   10-12 Children
• Paper Supplies
• 1 Party Attendant
• Balloons
• 2 Cheese Pizzas
Each additional Child is $16
Each additional Pizza is $12

H2K Premiere Party Package

$360   /   90 Mins   /   13-15 Children
• Paper Supplies
• 1 Party Attendant
• Balloons
• 3 Cheese Pizzas
• Your choice of kickboxing, Zumba, Yoga, or Hip Hop Class
Each additional Child is $18
Each additional Pizza is $12

H2K VIP Party Package

$500   /   2 Hrs   /   13-15 Children
• Paper Supplies
• 2 Party Attendant
• Balloons
• 4 Cheese Pizzas
• Goodie Bags
• Your choice of kickboxing, Zumba, Yoga, or Hip Hop Class
• Craft
• Frozen Yogurt Cake
Each additional Child is $20
Each additional Pizza is $12

H2K also holds private events for Sports teams, Bar/Bat Mitzvahs, Corporate Events, Girl and Boy Scouts, Mom Groups, Private Zumba and Yoga Parties for Adults, Baby Showers and Bridal Showers. Please contact for rental rates and information.



about us

H2K children fitness
Here at H2K, we've got plenty of accessories to get you in shape while having fun.
Tony Rinaldo, photographer
Tony Rinaldo, photographer


H2K’s new home is in Arlington at the Ready, Set, Kids! family enrichment center. We have a spacious studio, which is perfect for all of our fitness classes and birthday parties! The center is designed with families in mind, complete with a lounge and play area for kids. We also have a second location in Sudbury at Crossfit Union. In addition to our two locations, we offer a variety of mobile classes state and nationwide.

Julia Walderzak, Owner

Screen Shot 2013-04-21 at 9.18.35 PMJulia Walderzak is the founder of H2K Happy Healthy Kids Fitness Studio. H2K is a unique fitness studio that specializes in non-competitive fitness for children and families. They offer kids yoga, kids zumba, kids kickboxing, kids circuit training, mom and baby yoga, zumba with your toddler, teen classes, camps and healthy birthday parties.

Julia began her career as a corporate event planner, but felt unfulfilled. As a child, she struggled with her weight and hated competitive sports, so she taught herself how to get fit and maintain a healthy lifestyle in other, non-competitive, ways. Knowing there is a huge population of children and families that are currently struggling with the same issues she had overcome, Julia developed the concept for H2K. H2K was created in hopes of helping these families, who have been under-serviced in the past, learn how to live happy, healthy lives.

Julia currently has her 4th degree red belt in Tai kwon Do and also has certifications in zumba, kids zumba, kickboxing, and kids and teen yoga. H2K is slated to open its 2nd location this fall in Arlington, MA. It’s first location is located in Sudbury, MA.



2015BostonBestMedal_Top5BostonParents Paper

H2K Happy Healthy Kids Fitness Studio was proudly picked for the second year in a row for the best sports classes around Boston in their 2015 Family Favorite Awards, featured in their annual publication Best of the Best.

2014BostonBestMedalBostonParents Paper

H2K Happy Healthy Kids Fitness Studio was proudly readers’ picks for the best sports classes around Boston in their 2014 Family Favorite Awards, featured in their annual publication Best of the Best.

Hula FrogHula Frog

Come check out why Hula Frog names us one of the most Loved Party Places! H2K offers awesome healthy birthday parties. You get your choice of Zumba, yoga or a kickboxing party. All parties include paper supplies, balloons and pizza, and we have packages to suit every party need.


find us

284 Broadway
Arlington, MA 02474

Jam Time
86 Powder Mill rd
Maynard, MA 01754

Jam Time
251 West Central St
Natick, MA 01760

Emerson Wellness Center
310 Baker Avenue
Concord, MA 01742

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