fun now fitness forever !



H2K Classes

H2K offers a 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 cardio dance, yoga, circuit training, hip hop, play and pretend and tumbling. All of our classes provide a safe and nurturing environment in which every child is welcome, no matter the fitness level. We end each class with mediation and healthy goals to work on!

Tiny Kids Cardio Kickboxing (3.5-6yrs)

Tiny Kids Cardio Kick Boxing will improve your child’s strength, coordination and self-confidence through relay races, obstacle courses and games! We will introduce your little one to basic boxing choreography and core work. Your child will be introduced to meditation and healthy goals.

Kids Cardio Kickboxing(7-10yrs)

Kids Cardio Kickboxing will teach your child self-defense, self-confidence and discipline in a fun, safe and inclusive environment. We will learn different punches and kicks, boxing drills, bag work, non-contact sparring and work on core strength. We will end each class with healthy goals and meditation.

Kids Movement Classes 4-13yrs

Kids Movement classes range from hip hop, urban dance, 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.

Tiny Tot Tumblers (1-2yrs)

Improve your child’s fine motor skills with our super fun Tiny Tot Tumblers class! With the use of balance beams, hula hoops, games, and more you and your child will engage in a creative class, being introduced to basic acrobatics and tumbling to develop agility, balance, and movement.

Lil’ Hip Hoppers (4-7yrs)

Lil’ Hip Hoppers is a fun, upbeat, high energy Hip Hop dance class for young dancers. Students will be introduced to basic choreography and acrobatic movements to promote coordination and agility. Class will also incorporate dance games, stretching, and relaxation.

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.

Teen Yoga

This wonderful class is a combination of Kundalini and Hatha yoga with focus on breath work, meditation and partner poses. It is the perfect class to strengthen your mind, body and spirit, relieve stress and have fun!

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 suit your needs. 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.

Renew and Restore Yoga

Join Julia Walderzak, owner of H2K, for our brand new adult series, Renew and Restore. Julia begins class with core strengthening poses, balancing poses and hip openers. The last 30 minutes of class will include deeply relaxing restorative yoga poses with hands on energy work. This class is a perfect combination of total body strengthening and relaxation. All levels are welcome and postpartum and prenatal modifications will be given for our new and expecting mommies.

Curvy Yoga

This class is designed for larger men and women, and aims to create an atmosphere of comfort for all skill levels. Whether you are interested in beginning a yoga practice, or have been practicing for years, this class is a great space if you have previously felt uncomfortable in typical yoga classes. The class will incorporate stretching and strength poses, with modifications or props available to aid all members.

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 classes, camps, drop-off parties or night out events to your school, business, library, hospital or private event! We offer a variety of mobile classes statewide. We can tailor a class to suit your specific needs and schedule. Please email us at info@h2kchildrenfitness.com for rates and availability.


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


birthday packs

H2K offers fun and healthy mobile birthday party options for your child!

You provide the space, and we bring the fun! H2K offers different private, mobile party packages depending on your needs. Choosing H2K for your child’s birthday is a super fun and unique option.
The best part is that it’s a healthy option!


All classes will be led by certified H2K instructors, and will incorporate mindfulness and a short meditation. Choose from yoga, cardio dance, hip hop dance, Lil’ Ninjas or kids’ kickboxing.

All classes can be tailored to any age group, from toddlers to teens!


H2K Standard Party Package

$150   /   30 Mins
• 30-minute basic fitness class of your choice.

H2K Extended Party Package

$175   /   45 Mins
• 45-minute fitness class of your choice.

H2K Premiere Party Package

$225   /   90 Mins
• 45-minute fitness class plus games and obstacle course.
• Craft led by H2K instructor. Supplies are provided by H2K.



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

Julia Walderzak, Owner

Owner Julia Walderzak founded H2K Happy Healthy Kids Fitness 4 years ago outside of Boston. As a child, Julia 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 was huge population of children and families 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. Since becoming a new mom, Julia has experienced first-hand the importance of consciously maintaining physical, mental, and emotional health for both care takers and children alike. It’s her personal and professional goal to provide a resource for kids and families of all kinds to learn tools to stay happy and healthy in mind, body, and spirit.

Julia has a background in competitive Taekwondo and has received both gold and silver medals for sparring and form. She also has certifications in Zumba, kids Zumba, kickboxing, Radiant Child Yoga levels 1-3, and Yoga for Children with ADHD, Autism, and those who are Differently-Abled.

Visit Julia’s website at https://www.jwfitnesspreneur.com!


Hayley Chizinsky, Client Relations Director

Hayley Chizinsky is from Beverly MA, and has lived on the North Shore of Massachusetts for all her life. She graduated from Salem State University in 2017, where she received her Bachelor of Science Degree in Communications with a concentration in Media Studies and a minor in Philosophy. She was employed as a nanny for five years and has always loved working with children. She also has a background in cheerleading which helped develop her love for dancing and fitness.

She began her journey at H2K as their Social Media Marketing Intern during Summer 2016. That Fall, she started working as H2K’s Marketing and PR assistant, and by January 2017, she started to teach classes as well. She was promoted to Client Relations Director in September 2018. Hayley currently teaches cardio dance, hip hop, Lil’ Ninjas, and Tiny Tot Tumblers classes.

Sara O’Reilly, Product Designer

Sara O’Reilly, originally from Burlington MA, has been living in the Worcester community for six years. She received her bachelors degree from Salem State for Graphic Design. She currently works full-time as an Interior Design Assistant, and is becoming certified to be a yoga teacher. Her passion is her business that she owns that she has been building for the past few years, called SunnySide Upcycled. She refurbishes furniture as well as making custom rustic home decor and jewelry. 

She loves this opportunity she received to partner with H2K to design their retail product line! It combines both her love for design and able to work with a mindfulness fitness company. Her core value is her focus and determination to each and every customer. She prides herself in delivering high quality, customized and unique pieces that will stand out from the rest.



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.


Mailing Address

H2K Happy, Healthy Kids Fitness
10 Technology Drive Unit 218
Hudson, MA 01749

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