Our Staff

At Henry Mayo Fitness and Health, our experienced staff are here to help guide you to a healthier and active lifestyle. Take a look below to find out more information about some of our staff.


General Manager                         

Bill Holstein


Bill Holstein comes by fitness and sports naturally, growing up in the Chicago area.  He relocated to Los Angeles with his family where he played high school football, led his team to a league championship and was selected Offensive Player of the Year.  A severe knee injury ended his college athletics at the University of Idaho, where he graduated with a major in Sports Science and a minor in Business.  His love of the health and fitness field developed into a management career in fitness centers, working in both commercial and corporate settings.  Additionally, he began a training company, PowerFitness Training, LLC, which provided comprehensive wellness education, nutrition counseling and fitness training for groups and individuals.  Bill has coached youth and travel baseball in both Valencia and Castaic and has resided with his family in the Santa Clarita Valley for 12 years.



Director of Member Services  

Sharlene Duzick


Sharlene Duzick is well recognized in the Santa Clarita Valley fitness community. Prior to her new position, she was the Director of Member Services for the Santa Clarita Valley Family YMCA where she supported community members in developing a healthy lifestyle through personal one-on-one support and in group exercise settings.

“I always have enjoyed educating the community on how to live healthy while supporting and helping them obtain their goals in their wellness journey,” she said.

Duzick has always had a passion for health and wellness which started in high school where she played soccer and softball, then continuing when she became a marathon runner and triathlete.

She also coaches Students Off and Running (SOAR) a group that offers youth in need living in the Santa Clarita Valley the opportunity to participate in a fully supported, 24-week, 380-mile marathon training program.

“It’s very rewarding to work with young people in this program and to watch them as they accomplish something truly extraordinary in a non-competitive arena,” Duzick said.

As a longtime SCV resident, Duzick naturally gravitates toward local outreach and education for the community. She is a former Miss Santa Clarita Valley and a member of JCI Santa Clarita. Duzick is extensively involved in business and philanthropic projects in the SCV. She holds a bachelor’s degree in Business Marketing from California State University Northridge.



Fitness Director

Adnan Hyder


Adnan Hyder has been a certified personal trainer for 12 years, and for the past three years held the position of fitness manager at Equinox Fitness, an upscale line of fitness clubs in the Greater Los Angeles area. As a fitness manager, he has experience in new club openings and successfully opened three clubs in Woodland Hills, Westlake Village, and Glendale. Each club has continued to surpass the previous club in breaking records nationwide for sales revenue and personal training sessions performed.

“I look forward to helping the residents of Santa Clarita achieve their personal fitness goals by providing the best quality of personalized training available,” Hyder said. “Our health assessment tool uses resting heart rate, blood pressure, body composition and, strength and flexibility to determine customized programs for each of our members.”

In addition, Hyder has been involved in the initial onboarding and ongoing education of personal trainers regarding subjects such as physiology, anatomy, neuroscience, proper joint function and how all these subjects play a role in movement mechanics. Hyder received his bachelor’s degree in Physiology and Neuroscience from the University of California San Diego.








Personal Trainers