MEET THE TEAM

Within is a next-generation medical clinic and retreat center in Austin, Texas that blends cutting edge psychedelic science, traditional healing modalities and functional medicine to help clients transform their lives from within.

Our team of physicians, therapists, coaches, practitioners, and staff work in harmony to provide an enriching experience on your path to your highest potential.

  • This is a headshot of David Naylor - Founder.

    David Naylor

    Founder & CEO

  • Eric Miller, M.D.

    Medical Director, Within Clinic

  • Brittany Castañeda, MSN, FNP-C

    Clinical Director, Within Clinic

  • Sarah Turrentine

    Integration Manager

  • David Burks, LMSW

    Guide/Psychotherapist, Within Clinic

  • Dr. Meredith Aistrup

    Functional Medicine Doctor

  • Crystal Larkins

    Director of Business Development

  • Luke Carver

    Admissions Manager

  • Shannon Grossman

    Executive Director

  • Sarah Slack

    Psychedelic Guide & Integration Coach

  • Heather McCan

    Psychedelic Guide

  • Ashley Buchanan

    Psychedelic Guide

  • BriAnna Hermosillo

    Client Care Coordinator

David Naylor

Founder & CEO

David is an experienced Chief Executive Officer with an exceptional background in launching companies, along with a lifelong passion and deep personal journey of healing trauma, addiction, mental health and awakening consciousness through many different modalities such as Plant Medicine, Ancient Traditions, Gut Health, Microbiome, nervous system regulation, and mindfulness practices. After a long career with Google, David went on to launch 4 different healthcare companies that resulted in 4 treatment centers, 12 aftercare homes, with over 60 employees. His passion and purpose is healing and expanding consciousness, and transforming the current healthcare paradigm. David lives in Austin, Tx with his partner Mariya, two children, two dogs and enjoys playing pickleball, boating, and spending time with his community & friends where they get to live together in meaningful community & friendship.

Eric Miller, M.D.

Medical Director, Within Clinic

Dr Miller is a physician who specializes in Internal Medicine and Obesity Medicine, practicing since 2008. He is originally from New York, currently residing in Austin, TX. Dr Miller is particularly passionate about empowering people to take control of their health with diet and lifestyle choices, as well as by implementing other holistic treatments in order to achieve physical and mental well-being. Dr Miller is an IFBB Pro athlete and in his spare time enjoys exercising and spending time with his pup, Evey. 

Brittany Castañeda, MSN, FNP-C

Clinical Director, Within Clinic

Brittany is a nationally board certified Family Nurse Practitioner and certified BeingTrueToYou Psychedelic Integration Coach. With 8 + years of healthcare experience in a variety of settings, Brittany brings in a wealth of knowledge to Within. She earned her Bachelors of Nursing from UT Austin, her Masters of Nursing from Texas State. 

She has a passion for bridging ancient and western modalities and utilizing ketamine as a powerful tool for tapping into our inner healers and diving in for deep self discovery. She believes with this we can truly be on the path for healing and reconnection with ourselves and our purpose. As said by Sanaya Roman, “You have the greatest power of all, the ability to heal and evolve yourself”

Born and raised in San Antonio Texas, Brittany currently resides in Austin, Texas with her sweet Shih Tzu, Cooper. She enjoys traveling, immersing herself in nature,  all things DIY, and spending quality time with family and friends. She welcomes you to the Within family, together we can spread love, light, and heal together as a community. “A journey of a thousand miles begins with a single step” – Lao Tzu

 

Sarah Turrentine

Integration Manager

Sarah Turrentine began her journey of going within in 2019 and has since dedicated her time to turning her mess into her message. She finds great purpose in helping walk people through their shadow while remembering to enjoy the beauty that life offers. She believes that we all have the capacity to heal and that our healing journey can be fun and exciting when compounded with authentic connection. She has certifications as an L1Enlifted Coach, a Recovery Support Peer Specialist and is working towards a certification In Being True to You Transformational Recovery. When not working 1 on 1 with our residents or organizing fun and interactive social events for the community you will find Sarah singing loudly to herself while driving and basking in the sunshine.

David Burks, LMSW

Guide/Psychotherapist, Within Clinic

David Burks is a therapist and guide in Austin, Texas. David has been a committed student of meditation for over 15 years and has taught Mindfulness-Based Stress Reduction (MBSR) in hospital and University settings. He brings an experiential and somatic approach to therapy, having trained in Hakomi Therapy and also studying Internal Family Systems (IFS) and Accelerated Experiential Dynamic Psychotherapy (AEDP). His style is warm, relational, and present centered, and he has experience with people suffering from trauma, depression, anxiety, addiction, and spiritual crisis, with a special focus on spiritual growth.  David is interested in the sacramental use of psychedelics to enhance mental health, spiritual growth, and overall well being.

Dr. Meredith Aistrup

Functional Medicine Doctor

Dr. Meredith Aistrup completed her Doctorate of Naturopathic Medicine at Sonoran University of Health Sciences in Tempe Arizona. She received her bachelor of science in Molecular Biology from the University of Kansas. Dr. Aistrup believes that a client should be given the time and space to express their concerns and be deeply listened to and cared for. She utilizes therapies such as nutrition, herbs, supplementation, counseling, lifestyle medicine, environmental medicine, and mind–body medicine to address concerns. The mind, body, and spirit are all taken into consideration for deep healing.

When Dr. Aistrup is away from the office she loves traveling, hiking, camping, mountain biking, snowboarding, practicing yoga, and building community.

Crystal Larkins

Director of Business Development

Crystal has been on her own healing journey for the better part of the last decade. She is passionate and clear in her purpose of uplifting others to realize that healing comes from within. Her background in business and sales and passion for holistic wellness make her the perfect addition to the Within Business Development and Marketing team!

Luke Carver

Admissions Manager

Luke Cade Carver is from Denver Colorado. He works for Within doing PR, Marketing, sales and coaching. He has turned the dark times of his life and made those experiences become positive in helping others through their transformation. He believes that each and every moment is beautiful, good or bad. That through each moment something can be learned. Always working on growth and ascension he humbly helps those he meets. He loves yoga, working out, breathwork, sound baths and ecstatically dancing around Austin Texas. He embodies transformation.

Shannon Grossman

Executive Director

Hello! My name is Shannon Grossman, and I am serving in the Finance Dept. and I love it! I have been working with the sobriety field now for over three years. With a background in the Arts and Small Businesses, I have found a complete passion for helping people and small businesses get to the next level. There is nothing better than to realize, what you possess is a talent of inspiring someone else to believe in themselves, to walk with them until they can see the path of their own freedom.

That is exactly what we are looking to do, to breathe life back into sobriety, and help you get to the next level of you. I am very lucky to have this opportunity, work with a team, and collaborate with so many Mentors that share this same goal. I have once heard that if you truly love what you do, you never have to work a day in your life! I now know what they mean.

Sarah Slack

Psychedelic Guide & Integration Coach

Sarah is a born spiritual healer. Born and raised in Texas and spending the better years of her childhood just north of Austin. She has always had a gift of holding a safe space for others, and offering a listening ear that will leave you feeling seen and heard. Born into a family of pastors in a Protestant church, spirituality has always been a part of her life one way or another. Moving away from the dogma of religion, Sarah looks to her relationship with the divine spirit (God) for guidance, and moves through her life with integrity, authenticity, kindness, and love. She uses her gifts to help others find their way, connect deeper with themselves, move through life with more embodiment, enrich what is present, and inspire them to reach their dreams.

She is a guide and integration coach here at Within and facilitates meditation and yoga classes. Sarah offers a unique approach to ketamine therapy by using the skills she learned through massage therapy and from her own journey of healing through psychedelics. She has been a licensed massage therapist since 2010 and a certified yoga teacher since 2018. She’s been on an avid non-stop healing journey since 2019 by overcoming strong negative habitual patterns, addiction, re-connection to herself and spirit, and difficult life challenges.

She will use her intuition to help direct and anchor you through your ketamine journey. Using drums, sound bowls, essential oils and fans, while also offering energy healing and somatic holds to help you anchor into your reality, dive deeper with yourself in a safe and loving container, and find healing for your mind, body, and spirit. She listens to you deeply, will offer reflective feedback, will softly challenge both your thoughts and perspectives, and most importantly is a strong support for you during this time of healing and radical change.

Heather McCan

Psychedelic Guide

Hi, my name is Heather McCan. I am a somatically trauma-informed guide at Within Center.I have 14yrs experience working with plant medicines, participating in sacred ceremonies as a guardian and working in healing spaces. I have also been a licensed massage therapist since 2011. In 2016 I was liberated from a life-threatening addiction to alcohol in a sacred plant medicine ceremony. It was the beginning of a profound journey on a path of healing, recovery, and transformation. By the grace of God I found my way to the medicines, people, and healthy practices that helped save my life. I am here as a beacon of light and hope; True healing and transformation is possible. My heart’s greatest desire is to utilize all the knowledge I have attained and all that I have overcome to help others find their own inner healer.

I am a student of the divine and have the heart of a theologian. I love reading sacred spiritual texts and exploring the unseen realms. I enjoy snowboarding, hiking, music, dancing, concerts and going to transformative festivals. I have a little doggie named Vega… she is the light of my life!

Ashley Buchanan

Psychedelic Guide

Ashley Buchanan is a yogini, intuitive healer, guide, priestess, mentor and clairvoyant empath. She believes that all souls came to this Earth with their own mission, medicine and magic. She is here to support the release of blockages that are affecting your reality, open channels, and restore your energy to a state of equilibrium. Ashley is passionate about serving others along their journey of self-discovery, shining light on your own divinity to help you remember who you are and what your soul came here to do. To unleash your power, unlock and activate your gifts, and amplify your fullest, most authentic expression. To help bring you into alignment with your soul destiny. Through experiential wisdom, channeled guidance, light language activations and quantum field work, Ashley facilitates healing, harmony and ascension for your soul’s highest and greatest good.

BriAnna Hermosillo

Client Care Coordinator

BriAnna was raised in Texas by her immigrant grandmother who practices indigenous healing modalities and plant medicine known as curanderismo. Having been taught the ways of the ancestors, she decided to further her education in curanderismo back in 2020 at the University of New Mexico, having completed the educational program taught by Professor Don Eliseo Torres. BriAnna continues to be of service to humanity, inspired by Loved ones; her grandmother and uncle Dr.Geraldo Hurtado who was a theologian and medicine man. In her leisure time, BriAnna enjoys dancing, cooking, making art, and curating healing spaces and events for her community. She is very grateful to be a part of the Within Family, helping others on their healing journey and initiation into ceremonial medicine.

Schedule an initial consultation with us today

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