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About our team

About Us

Holly Peng MD

Family Physician and Integrative Health Coach


"I believe the foundation of "being the best version of you" and "living life to its fullest" is having HEALTH. And health is not the absence of disease but an optimal state of mental, physical and spiritual well being. I believe that everybody in this world can tap into that deserved authentic health and there is nothing more important.

Growing up with my grandmother (who lived until she was 105) I would hear her mantra in my ears -"watch over your health- without it, nothing else matters".  All the money in the world would be useless without your health. Without your health, you cannot be en effective parent, worker, or leader.

I believe furthermore that we were put on this earth to experience an exuberant life and the power to attain it is inside each one of us.

Here at Island Trek Fitness, we are dedicated to helping you achieve this exuberant life."

Dr. Peng is the founder, owner, and manager of Island Trek. She has practiced clinical medicine for the past 20 yrs for Group Health and Kaiser Permanente and now is self employed as a contract/locums provider. Holly grew up in Tuscon, Arizona and received her undergraduate degree at the University of Chicago, medical degree at the University of Arizona School of Medicine. Holly completed residency in Family Medicine with University of Washington and Group Health. Dr. Peng is board certified in Family Medicine and has a Diploma in Tropical Medicine and Disease through the London School of Tropical Medicine. She is thrilled to be a Integrative health coach, a graduate of the Institute of Integrative Nutrition. Holly lives in Seattle, Washington and is the proud mother of her labradoodle Barkley.

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Marcie Costello LMT, RYT, CRM

Yoga Instructor Reiki Master

Licensed Massage Therapist

"I teach from my heart and I am so grateful for all the students who come and share their beautiful souls- they inspire me more than they could ever know."

Marcie Costello is the founder of Shakti Yoga and Wellness. She is passionate about the many healing benefits that yoga offers and is appreciative everyday for the privilege to share such a beautiful practice with others. She believes that through the practice of yoga, there is no limit to how much one can grow physically, emotionally and spiritually.

Marcie has been practicing yoga for over 20 years. She is RYT 500-hr Yoga Alliance Certified. Her formal training was through Yandara Yoga Institute , Teacher Trainer and Course Development at 200 and 300 hour level programs.

Marcie graduated from the Utah College of Massage Therapy in 1998 and has completed nearly 1500 certified hours in various modalities of massage. She is also a Reiki level Master/Teacher with study interests in Pranayama, Meditation, Ayurveda, Sanskrit, Mantra, and Ritual Ceremony.

Whether on the mat or on the massage table, she inspires her clients to calm the nervous system while honoring their boundaries of the mind, body, and spirit. She offers subtle adjustments with an emphasis on safety.



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