John A. Duffy Jr., Founder

“The Short” of It…

John is the mastermind behind the Cardio Sport™ Exercise System.  John’s deep knowledge of how the human body functions, coupled with his supreme mastery of how to apply his knowledge to get elite results, has been the foundation from which the Cardio Sport Exercise System was developed.

Over the past decade, through Cardio Sport, John has personally trained  thousands of people (athletes and regular people) with extraordinary results.  Over the past 2 years, he has also taught hundreds of instructors, trainers, athletes, PE teachers and coaches to use his methodologies through Cardio Sport’s national certification initiative.  Using his system and philosophies, Certified Cardio Sport Instructors around the nation have achieved outstanding results within their own participations.

John’s exceptional skill and mastery of his expertise is demonstrated year after year through the thousands of people who have changed their bodies and lives as a result of Cardio Sport.

And “The Long” of It…

Growing up John was a skilled athlete, playing numerous sports, including soccer,  hockey, basketball, lacrosse, baseball and tennis at the high school, collegiate and post collegiate level.  Always the team captain, he was a passionate athlete that dedicated thousands of hours to training and practicing for his sports. As he became older, it became very apparent that although John has natural skill, he had a unique ability to understand how to train his body to maximize his results and performance in the game.

In addition to a love of sports and physical movement, John is also intensely passionate about music and the psychology of people. Both of these life long fascinations play a key role in his development of Cardio Sport, and ultimately the program’s phenomenal success. For a  fitness program to be truly successful over a long period of time, it must produce far more than just physical results. John’s clear understanding of this concept early on, coupled with his keen ability to create an environment that inspires and motivates people to achieve more than they could ever imagine possible, has been life changing for many and created Cardio Sport’s success.  Cardio Sport participants around the country will tell you that they are impressed by the fitness results they receive, but even more impressed by how their participation in the classes has impacted them mentally and emotionally. 

John graduated from Adelphi University with a BS in Finance and began his entrepreneurial endeavors by the age of 25. He has owned and operated three companies and today chooses to focus his energy,  passion, extensive experience and knowledge into the Cardio Sport national initiative.

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Hilary Hartman, VP Marketing & Business Development

Hilary heads up sales, marketing and brand development. She became involved with Cardio Sport over 3 years ago as a participant. She is a long time entrepreneur, with over a decade of experience in business and product launch strategy.

Having been raised in an entrepreneurial environment as a child, Hilary knew from a very young age that she would some day work for herself – she just wasn’t sure when or what it would be. After college, she launched her career in the corporate world and spent several years working to gain the knowledge to break out on her own. By 29, she began as strategic consulting firm that focused on medical device clients.  Six years later she had built a very busy and successful firm, which regularly employed 7-10 other consultants and served over 30 different companies, including all of the major players in the medical device industry and a number of up and coming start ups.

In the Fall of 2013, she was a point in her life where she wanted more than just financial success. She wanted to apply her knowledge and skills to something she was truly passionate about. After a class one day, she had a casual discussion with John regarding Cardio Sport’s national business strategy. She was intrigued and offered to help co-write the business plan for this new arm of John’s business. She always knew that Cardio Sport was something special – not just another fitness program, but after diving into the project, she began to recognize  the significant business opportunity that Cardio Sport presented.

After working on a few projects here and there, and maintaining her firm, she hit the proverbial fork in the road that every entrepreneur eventually meets. Go forth in full or step back…So she made her decision and in 2014,  she  jumped in head first to follow her passion. She exited her consulting firm and began her journey to focus full time on building Cardio Sport’s National Certification Program. Things have been fast and furious ever since, but she has never looked back.  Every day she is thankful to have the opportunity to devout her passion, enthusiasm, experience and knowledge to something she truly loves.

In January 2015, Hilary became a Partner in Cardio Sport.  Hilary holds a BA in Communications from the University of Massachusetts  at Amherst and an Executive Management Certificate from Northeastern University.

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Katie O’Connell, Weymouth Studio Lead / National Corporate Instructor

Katie is a long time athlete, who played soccer competitively throughout her high school and college years.   When she stopped playing on a team, she found herself uninspired by other fitness options out there. Like many athletes, Katie’s first Cardio Sport class changed her life. She connected to the challenge-based, play filled, team sport feel because it gave her a purpose and passion for physical movement again. It was this connection that lead her to pursue a deeper understanding of Cardio Sport’s method, and ultimately to where she is today. Katie runs the Cardio Sport Weymouth Studio and is an integral part of our National Corporate Instructor team. Katie graduated from Clark University.


Mara Murphy-Kusins, Inside Support Trainer / National Corporate Instructor

Mara played both soccer and hockey in her high school years. It was her passion for movement that lead her to become a Cardio Sport Instructor almost three years ago. Mara is an Inside Support Trainer who instructs in the Corporate studios, and works directly with our national client-base  to provide post-certification support for successful implementation of  the Cardio Sport Training methodology. Mara loves working with our clients to share her passion for Cardio Sport, both in teaching classes and helping other instructors learn to lead classes around the country. Mara is a long time Duxbury resident and holds a business degree from Lasell College.


Jacelyn Rhoads, National Corporate Instructor

Jacelyn became involved in fitness through the Cardio Sport program several years ago. As a participant she worked exceptionally hard and became one of the most outstanding athletes within the program. Helping people to achieve fitness goals grew into her passion, and she became both the first Certified Cardio Sport Instructor and Cardio Sport Certified Trainer. Jacelyn is on our corporate instructor team. She attended Northern Arizona University and then worked for several years in the Boston Financial District prior to finding her true passion.


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