Gus Castellanos, M.D. attended the University of Miami undergraduate and Medical School, receiving his M.D. degree in 1980. He trained at Emory University School of Medicine, Georgetown University School of Medicine, and the University of Texas MD Anderson Cancer Center. He received Board Certification in Neurology in 1987 and in Sleep Medicine in 1994. He was Assistant Professor in Neuro-Oncology at MD Anderson Cancer Center before relocating to practice Neurology & Sleep Medicine in Palm Beach County, Fl, in 1987. In 2006, he retired from the practice of Medicine. He trained and received certification to teach MBSR by the University of Massachusetts Medical School Center for Mindfulness in Medicine, Health Care, and Society in 2017. He trained with and contributed to Amishi Jha Mindfulness Based Attention Training at the University of Miami and trained to teach Mindfulness Oriented Recovery Enhancement with its developer, Eric Garland of the University of Utah. In 2020 Dr. Castellanos was hired as an Adjunct Instructor by Nova Southeastern University to teach and research mindfulness-based programs.