About Us

The Proactive MD Team

We’re impacting the healthcare system at the source.

We make it easy for you to get comprehensive care for yourself and your family. As your onsite healthcare clinic, Proactive MD provides you with compassionate primary care physicians and a dedicated care team who can offer guidance and support as you navigate your healthcare journey.

Meet Our Team

Team

+ Meet John

John Collier

Founder, President & Chief Executive Officer

John Collier

Founder, President & Chief Executive Officer

John Collier


John provides the overall vision and direction for Proactive MD, continuously finding new ways to serve our patients and employers through strategic planning, executive management, innovation, and strategic partnerships.

John is the former CEO of Palmetto Proactive Healthcare, a South Carolina-based Direct Primary Care provider. His previous professional experience leading direct to employer contracting for one of the largest hospital systems in the country gives him a deep understanding of the unique ecosystem of health systems, payors, and employers. John brings 15 years of in-depth knowledge of healthcare management and strategy to Proactive MD with his background in healthcare administration, payor contracting, provider network development and employer cost containment plan design. John is a Fellow of the American College of Healthcare Executives and a member of The Young President Organization (YPO). He earned his MBA and MHA at Grand Canyon University.

A self-proclaimed “healthcare nerd,” John enjoys researching the industry and learning new ways to improve the system for the people who need it most. John lived in Mexico for a time and is fluent in Spanish. He is a lifelong St. Louis Cardinals fan and loves Arizona Wildcat basketball. But most of all, he loves to spend time with his wife and three children.

John Collier

+ Meet Mark

Mark Kemble, MD

Executive Vice President, Medical Affairs

Mark Kemble, MD

Executive Vice President, Medical Affairs

Mark Kemble, MD


Dr. Kemble’s responsibilities include medical leadership and oversight of all Proactive MD Health & Wellness Centers, the development and implementation of clinical policies and protocols, and clinical supervision of physicians and providers.

Dr. Kemble is an accomplished physician with over 20 years’ experience in family medicine and onsite health. Dr. Kemble graduated from the Medical University of South Carolina and completed his decorated residency at Greenville Hospital System, where he was honored with Outstanding Resident of the Year award, Lily M and G.D. Jackson Award, and Outstanding Clinical Achievement Award. Dr. Kemble went on to own and manage all aspects of his family practice for over 15 years and then served as the Medical Director of a large onsite health center before coming to Proactive MD.

Mark Kemble, MD

+ Meet Kevin

Kevin Guion

Chief Administration Officer

Kevin Guion

Chief Administration Officer

Kevin Guion


Kevin is responsible for strategic planning, M&A activity, and operational oversight of Proactive MD’s corporate service center, which includes financial management, human resources, marketing and public relations, sales support, general counsel, risk management and compliance, and administrative operations.

Kevin has been leading operational teams for over 25 years, with his most recent roles including serving as COO for South Carolina’s Department of Health & Environmental Control and President & COO for OB Hospitalist Group. Kevin has served as a speaker, panelist, consultant, and executive coach for driving transformational change and navigating rapid-growth business environments. Kevin earned both his undergraduate degree in Marketing and his MBA at Baylor University. Kevin enjoys spending time with his wife and six children, traveling to cheer on his daughters at their soccer games, and serving as the President of a local Middle School Band.

Kevin Guion

+ Meet Byron

Byron Revels

Executive Vice President, Growth Strategy

Byron Revels

Executive Vice President, Growth Strategy

Byron Revels


Byron is responsible for leading the Proactive MD Business Development team and developing new relationships with employers, benefits brokers, and wellness consultants. Byron also helps drive innovation and develop new ways to serve our employers through Proactive MD’s Advanced Primary Care Health & Wellness Centers.

Byron has 10 years of onsite clinic experience. He worked with large onsite healthcare services delivery organizations and co-founded Verimoov, LLC. Byron has extensive experience with clinic operations, reporting and analytics, and designing effective engagement strategies and has a degree in business from Clemson University. Byron spends his free time with his wife and their goldendoodle Graham, traveling and eating way too many wintergreen mints.

Byron Revels

+ Meet Troy

Troy Corley

Executive Vice President, Service Delivery

Troy Corley

Executive Vice President, Service Delivery

Troy Corley


Troy is responsible for providing leadership to our employer facing account management team while also focusing on the patient experience and engagement within our Health & Wellness Centers and the communities they serve.

Before joining the Proactive MD team, Troy worked in the premium home services field for 10 years, where he played a vital role in adding massive growth to the organization and led the company to receive national recognition for its industry-leading customer service. Troy has expertise in developing company cultures that promote excellence in all areas and foster service-minded employees. Troy earned his Bachelor of Arts in History from the University of South Carolina. When not enjoying his favorite pastime of spending time with his wife and two children, Troy dabbles in a multitude of hobbies that include beekeeping, woodworking, cooking, reading, and cheering on the South Carolina Gamecocks.

Troy Corley

+ Meet Leigh

Leigh Ford

Associate Vice President, Marketing & Communications

Leigh Ford

Associate Vice President, Marketing & Communications

Leigh Ford


Leigh is responsible for leading the Proactive MD marketing and communications team, directing internal and external communications, developing and implementing promotional campaigns, and providing the sales team with resources and support.

Leigh has 8 years’ experience working in healthcare, with the most recent being at the South Carolina Department of Health & Environmental Control (DHEC) as the Director of Strategy and Continuous Improvement. Leigh also has a background in data analysis, research, and strategic planning, having served at the South Carolina Office of Regulatory Systems for 9 years in Electric and Natural Gas Regulation. Leigh earned a Bachelor of Arts degree in Communications and Spanish from Lenoir Rhyne University. An avid South Carolina Gamecock and Boston Red Sox fan, Leigh enjoys spending time with her family, volunteering at church and in her community, and traveling to Boston as often as she can.

Leigh Ford

+ Meet Jeremy

Jeremy Vanderknyff, PHD

Associate Vice President, Program Value

Jeremy Vanderknyff, PHD

Associate Vice President, Program Value

Jeremy Vanderknyff, PHD


Jeremy’s responsibilities include designing and executing Proactive MD’s informatics strategy, projecting return on investment and population health impact to prospective clients, and reporting the clinical and financial performance of Proactive MD Health & Wellness Centers.

Jeremy has 10 years’ experience in clinical operations and health informatics at the South Carolina Department of Health & Environmental Control (DHEC), where he served as a Lean Six Sigma consultant and, most recently, served as Director of Project Management, building and leading the agency’s first enterprise Project Management Office. Jeremy has served as an expert panelist and consultant for public health data systems and organizational performance management. He earned his PhD in Medical Anthropology from the University of South Carolina. In his free time, Jeremy serves on the board for a nonprofit promoting and preserving South Carolina’s cultural heritage through archaeology education and outreach. He enjoys spending time with his family, who kindly request that he please stop playing the banjo in the house.

Jeremy Vanderknyff, PHD

+ Meet Bob

Bob Masteller

Vice President, Employer Engagement

Bob Masteller

Vice President, Employer Engagement

Bob Masteller


Bob is responsible for serving as a subject matter expert within the industry. He provides employers, benefits brokers, and wellness consultants with insights into the design and operation of successful onsite clinic solutions, and specifically the advantages of the Proactive MD Advanced Primary Care model.

Bob has 25 years of experience in Human Resources, 15 of which were spent as the Vice President of Human Resources at a company with over 6,500 employees. There, he was responsible for safety, environmental, legal, risk management, and human resources in the United States, Mexico, and South America. During his time with the company, he successfully implemented two onsite clinics with over 2,500 members each. Prior to entering the Human Resources field, Bob worked as an Industrial Engineer for 6 years. Bob earned a Bachelors of Science in Industrial Engineering from Geneva College and a Masters in Human Resource Management from the University of Alabama. He is SPHR Certified, Black Belt Six Sigma Management Certified, DDI Certified, and served on the Board of Directors for the Tennessee Automotive Manufacturing Association. Bob lives on a farm, where he enjoys letting his wife take care of their chickens, cheering on the Nashville Predators and the Crimson Tide, and beekeeping. His favorite pastime is planning trips and traveling to interesting destinations.

Bob Masteller

+ Meet Christi

Christi Coleman

Vice President, Employer Engagement

Christi Coleman

Vice President, Employer Engagement

Christi Coleman


Christi is responsible for serving as a subject matter expert within the industry. She provides employers, benefits brokers, and wellness consultants with insights into the design and operation of successful onsite clinic solutions, and specifically the advantages of the Proactive MD Advanced Primary Care model.

Christi has 27 years of experience in strategic consulting and sales focused on wellness and worksite clinics. She spent 23 years with a large occupational healthcare organization, where she helped to develop the wellness/worksite product offering, create a go to market sales strategy, and execute and sell the service offerings. Christi graduated with a Bachelor of Arts focused on Marketing and Sales from Baylor University in 1991. Christi enjoys traveling with her 3 sons and her husband of 25 years and supporting her sons in all their sports activities.

Christi Coleman

+ Meet Chris

Chris Flowers

Vice President, Employer Engagement

Chris Flowers

Vice President, Employer Engagement

Chris Flowers


Chris is responsible for serving as a subject matter expert within the industry. He provides employers, benefits brokers, and wellness consultants with insights into the design and operation of successful onsite clinic solutions, and specifically the advantages of the Proactive MD Advanced Primary Care model.

Chris previously worked in the onsite healthcare space as a Client Relations Manager. Before his career in onsite healthcare, he worked in the Pharmacy Benefits Management industry as a business development executive. Chris has more than 20 years of sales and account management experience in multiple healthcare verticals. Chris enjoys spending time on the soccer field with his wife and two sons.

Chris Flowers

+ Meet Anne

Anne Gibson

Vice President, Employer Engagement

Anne Gibson

Vice President, Employer Engagement

Anne Gibson


Anne is responsible for serving as a subject matter expert within the industry. She provides employers, benefits brokers, and wellness consultants with insights into the design and operation of successful onsite clinic solutions, and specifically the advantages of the Proactive MD Advanced Primary Care model.

Anne has 9 years of experience working for a large consultant firm, where she was responsible for developing strategy and deploying tactics to address risk factors within employer populations. She is a subject matter expert in onsite clinics and specialty pharmacy. Anne has also worked as a dietitian and has a degree in Nutrition from the University of North Florida and a Masters in Public Health Nutrition from Case Western Reserve University. Anne enjoys traveling and playing golf with her husband and two sons.

Anne Gibson

+ Meet Karen

Karen Davis, LPN, BSBA

National Director, Clinical Services

Karen Davis, LPN, BSBA

National Director, Clinical Services

Karen Davis, LPN, BSBA


Karen is responsible for leading the Proactive MD implementation team and working with operations to ensure compliance with clinical policies and procedures.

Karen has 35 years of experience in the nursing profession, including 28 years in employer-sponsored onsite healthcare management. She also has experience in the hospital medical and surgical field, home health, and as a Clinical Research Associate for a generic drug manufacturer. Karen earned her Bachelor’s degree in Business Administration from West Virginia University. In her free time, Karen enjoys cooking, baking, college football (Go Mountaineers!), and spending time with her great niece.

Karen Davis, LPN, BSBA

+ Meet Stephanie

Stephanie Saenz

National Director, Talent Acquisition

Stephanie Saenz

National Director, Talent Acquisition

Stephanie Saenz


Stephanie is responsible for leading the recruitment team in identifying, engaging with, and acquiring providers, clinical staff, and service center staff who will successfully carry out Proactive MD’s commitment to service and excellence.

Stephanie has 10 years of experience in healthcare recruiting. She previously worked as the Manager of Clinical Recruitment for OB Hospitalist Group, where she was responsible for leading physician recruitment and credentialing teams from sourcing and vetting candidates through the entire onboarding process. Stephanie has a Bachelor of Science degree in Business Administration from Southern Wesleyan University. Her hobbies include photography, reading, boating, traveling, and spending time with her family.

Stephanie Saenz

+ Meet Westley

Westley Roberts

National Director, New Employer Engagement

Westley Roberts

National Director, New Employer Engagement

Westley Roberts


Westley is responsible for serving as a subject matter expert within the industry. He provides employers, benefits brokers, and wellness consultants with insights into the design and operation of successful onsite clinic solutions, and specifically the advantages of the Proactive MD Advanced Primary Care model.

Westley earned a Bachelor of Science degree from Clemson University in Business Management & Entrepreneurship. He interned with Raymond James Financial while still in school. During his senior year of college, Westley met John and other members of the Proactive MD team and began helping with projects. He was hired shortly after and began working at Proactive MD just two days after graduating! Westley enjoys watching Clemson football, playing in local soccer leagues, and golfing. Together, he and his wife are committed to spending time with extended family and serving in their local church.

Westley Roberts

+ Meet Amber

Amber Geathers, MSW, LISW-CP

Senior Patient Advocate

Amber Geathers, MSW, LISW-CP

Senior Patient Advocate

Amber Geathers, MSW, LISW-CP


Amber is responsible for providing guidance, direction, and training for our Patient Advocates and for leading the Patient Advocacy program. Amber continues to provide support and guidance for members within local Health & Wellness Centers while maintaining a strong presence within the corporate service center to guide and support the Patient Advocacy program.

Amber completed her undergraduate and graduate Social Work degrees at Winthrop University. Her career focus is Case Management and Care Coordination. She is a member of the American Case Management Association and is a Licensed Independent Social Worker for Clinical Practice. This enables Amber to not only provide excellent resources and care coordination, but also to work independently to provide evidenced-based therapy and counseling. Amber is an Adjunct Professor at St. Joseph College of Maine teaching Social Work undergraduate classes. Amber’s favorite pastimes include traveling, hiking, reading current events, trying new cuisines, saving the world and spending time with her husband and two kids.

Amber Geathers, MSW, LISW-CP