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"Stefanie has been such an amazing trainer. She is very knowledgeable in what she does. I'm very grateful to have in in my life. She has helped me accomplish a lot both with physical and nutrition. She will push you to your goals and teach you every step of the way!" - Alisha

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Stef Callens

Voted Top 20 on Denver's A List for Best Personal Trainers in 2018 & 2016  

Owner of Vitality Training Studio, Located in Littleton, CO 


Hi guys! Thanks for stopping by my page. You're probably wondering who this Stef Callens person is and what makes her different than all the other personal trainers out there. 

Honestly, there are a ton of great trainers and you'd most likely get results with with any of them. So I'm not going to put anyone else down to try and get you to train with me. Instead, I'll tell you about myself so you can decide if I'm the right fit for you. 


Age: 30s (A woman isn't supposed to share their real age)

Training Philosophy: My goal is ultimately to get my clients to lead a healthier life - to be able to teach them how to incorporate exercise and healthy food choices into their lifestyle. I want my clients to be strong, confident and proud of themselves, while also extending themselves grace. There's so much in this world that causes us all to have possible self-esteem issues and I want to change that. I don't look like a bikini model, so I don't expect my clients to have those goals (no offense to another who has that goal, but I think that's shallow). 

Food Weakness: Dried Mangoes (no sugar added), Barely Naked Popcorn, kettle potato chips and watermelon. I can make a serious dent in either on the way home from buying them from the store

Favorite Meal: Breakfast - it's the most important meal of the day, right? I can eat most types of breakfast food all day long

Least Favorite Veggie: Eggplant. Not even sure what that is.

Favorite Type of Exercise: Almost everything - but running and especially anything with a sled, the heavy rope or slam ball

Least Favorite Type of Exercise: Assault Bike - seriously does anyone actually like that piece of equipment?

Favorite Part of my Body: Arms - hence the obsession with #ShowYourFlex

Least Favorite Part of my Body: Stomach

Favorite Moment Being a Trainer: This may sound cheesy but that aha moment for a client when they realize they can actually do something they struggled with in the past - or when they were convinced they couldn't do something but I proved to them that they can do it

Moment that Scarred Me Forever: 4th grade on the school bus this kid told me I had thunder thighs...jerk

Home State: I'm a true Jersey Girl (aka snotty about some food) - but moved to CO in 2012 and have no regrets

Family: Husband, 2 daughters (born 2018 and 2020) and dog (named Jersey).

Typical Client Experience: I have experience training both men and women, aged 14-87 and I love them all. Now that I have gone through pregnancy and postpartum myself, I love to work more with new moms - to teach them to love their current bodies, to focus on strengthening their bodies to support handling an infant and possibly other toddlers (not to just lose the baby weight), and to make sure that issues resulting from pregnancy does not plague them. I also specialize in training cyclists and women in the perimenopause and menopause stages.

Education: Bachelors and Masters Degrees in Computer Engineering from Villanova. Certified Personal Trainer through ACE. Training is my 2nd career. After 10+ years in the corporate world, I was miserable. So I decided to take the leap and follow my passion. Talk about scary! But I have no regrets! I absolutely love my job! I get so excited helping people get on the road to health! 

Certifications: I am certified through a legit place. I love to learn so I've continued to get more certifications and attend workshops. 



  • Certified Personal Trainer, American Council on Exercise (ACE) since 2013

  • Certified Online Personal Trainer, Online Trainer Academy

  • Certified Pregnancy and Postpartum Athleticism Coach

  • Certified Menopause Specialist

  • Certified Women's Health Specialist (GGS)

  • Certified Postnatal Fitness Specialist

  • ACE Fitness Nutritional Specialist (can help develop food plans that will compliment workouts)

  • ACE Weight Management Specialist

  • Function Movement System (FMS) Level 1 Certified

  • CPR/AED and First-Aid, American Heart Association


Specialized Training Received:

  • Pre and Post Natal Training

  • Corrective Exercise

  • Overweight and Obese Training

  • Integrated Hip and Core Training

Experience Training with:

  • Pre and Postnatal clients

  • Chronic knee pain (little or no cartilage in knees)

  • Clients battling obesity

  • Hip/Glute injuries

  • Shoulder/scapula injuries

  • Weak Ankles

  • Sciatica

  • Menopause & other hormone conditions

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