SDRehabACTion - 2025 Speakers

Dr. Gregory W. Lester

Gregory W. Lester, Ph.D. is a clinical psychologist licensed in Colorado and Texas. He has been in practice for over 40 years, has personally evaluated and treated over 3500 patients, and travels widely to speak at conferences and teach continuing education seminars. In his specialty of personality disorders, Dr. Lester has trained more human services professionals than any other individual, having presented over 2,000 trainings to over 250,000 professionals in 132 cities across the globe.

Dr. Lester is the author of four best-selling clinical manuals on the diagnosis and treatment of personality disorders, as well as Power with People, a manual of interpersonal effectiveness that is currently in its second edition and twentieth printing, Shrunken Heads, an irreverent memoire of the rigors of his graduate school training, and Central Intelligence Bureau: The Shrink, the Chip, and the Spy, a spy thriller novel series. Dr. Lester’s research and articles have appeared in many professional and popular publications, including The Journal of the American Medical Association, The Western Journal of Medicine, The Journal of Behavior Therapy, The Journal of Marriage and Family Therapy, The Yearbook of Family Practice, The Transactional Analysis Journal, Restaurant Hospitality, and Black Belt Magazine.

Dr. Lester lives in Colorado, where in his off-hours he is a marathon runner and mountain-climber, as well as an avid skier, marksman, certified Corvette race driver, and extra-class amateur radio operator. He is also a Master instructor at the largest martial arts school in Colorado, where he holds fifth-degree black belts in both traditional Tang Soo Do and Olympic-style Taekwondo, and was named “Instructor of the Year.”

Amberley Snyder

Amberley was born in California as the second to six children. Amberley fell in love with horses at a young age and began barrel racing when her family moved to Utah at the age of 7. She competed in Junior rodeos and up into high school, winning multiple titles and awards. Her senior year she finished as the National Little Britches World All Around Cowgirl.

In January of 2010, Amberley was involved in a rollover truck accident, leaving her paralyzed from the waist down. Eighteen months after that day, with a seatbelt on her saddle, she returned to competing in rodeo. She now competes in Women’s Professional Rodeo Association in barrel racing. Amberley made the Wilderness Circuit Finals in 2021 and 2022.

In 2018, Netflix released a move based on her life titled Walk Ride Rodeo where Amberley was able to be her own stunt double for the film. As a keynote speaker, professional barrel racer, author and actor, Amberley shares her story of triumph over tragedy hoping she can motivate others to believing themselves and get back on the horse

Parker Hanson

Parker was born without his left hand, but despite that he accomplished his childhood dream of playing professional baseball. Since retiring from baseball, Parker is now a Financial Advisor at Merrill Lynch, but also travels the country as a Motivational Speaker, sharing his story of Rise Above, No Excuses. In his message, Parker gets vulnerable about challenges he faced and provides applicable tools others can use to overcome obstacles they may face, while shedding light on both visible and invisible disabilities. His mission as a speaker is to inspire people to live positively today, because tomorrow isn’t promised.

Ashlea Lantz

Ashlea Lantz is a Senior Consultant with Griffin-Hammis Associates. She provides training and technical assistance around Customized Employment, Supported Employment, Self-Employment, Benefits Planning, and Agency Capacity Building. Before joining Griffin-Hammis Associates, Ashlea was the Director of Employment of a community-based rehabilitation agency. She has extensive experience in working with families both personally and professionally. Ashlea is a Certified Rehabilitation Counselor (CRC), a certified benefits planner, and has a master’s degree in Rehabilitation Counseling from Drake University. She also completed a Legislative Fellowship with CSAVR in 2025, further deepening her expertise in disability policy and systems change. Ashlea is passionate about business engagement and helping employers understand the value proposition of disability employment—demonstrating how inclusive hiring drives innovation, strengthens workplace culture, and supports bottom-line growth.

Jana Burke

Jana Burke, PhD, ADAC is the president and founder of Mariposa Professional Services, a consulting firm specializing in ADA compliance strategies for organizations with rights and responsibilities under the law. She is a small business owner, consultant, trainer, and researcher who specializes in the ADA employment provisions and workplace strategies for ADA compliance. She's also part of the Great Plains ADA Center team as their social media manager and ADA consultant. She lives in Colorado Springs with her son, 2 dogs, and 2 cats.

Trevor Manthey

Dr. Trevor J. Manthey is a highly effective presenter and seasoned trainer, known for his expertise in Motivational Interviewing (MI). With a Ph.D. from the University of Kansas and a Master of Social Work from Eastern Washington University, Dr. Manthey has dedicated over 20 years to refining and teaching MI, influencing positive behavioral changes across various professional contexts.

As a member of the Motivational Interviewing Network of Trainers (MINT), Dr. Manthey consistently delivers engaging and impactful training sessions, fostering agency cultural shifts that foster empathetic, strengths-based communication strategies. His ability to translate complex MI concepts into practical, actionable techniques has empowered thousands of professionals in mental health, vocational rehabilitation, healthcare, and correctional settings.

Dr. Manthey’s dynamic presentation style, combined with his deep commitment to evidence-based practice, positions him as an influential voice in the field, significantly enhancing client engagement and therapeutic outcomes through his training and consultation.

Ashley Zimmer-Larsen

Ashley Zimmer Larsen, LPC-MH (S), ATR, NCC, CCTP, TCTSY-F is an art therapist, mental health therapist, and trauma-sensitive yoga facilitator in Sioux Falls, South Dakota. She practices at The Wellness Collective and serves individuals across the lifespan, from children as young as three to adolescents and adults. For the past several years, she has dedicated her practice to supporting survivors of sexual abuse and domestic violence. In addition to art therapy and trauma-sensitive yoga, Ashley holds specialized training in play therapy and sandtray therapy. Ashley's unique ability to pull from a variety of approaches offers accessible, gentle, and effective ways to address the complex impact of trauma on the mind and body. Ashley currently serves on the board for Journey of Hope, a non-profit providing arts programming in a local juvenile detention center and other community locations. In her spare time, Ashley is working to build a community of creative arts therapists and artists working in healing and community settings through an initiative called Arts in Healing – South Dakota. She believes art is a powerful healing tool and community-builder.