Dr. Fellner earned his B.A. (2000), M.A. (2004), and Ph.D. (2012) degrees in Economics from Vienna University of Economics and Business. He also completed coursework background in the philosophy of science, evolutionary biology, complex dynamic systems, and chaos theory at the University of Vienna. He has served as a researcher at the Institute for Institutional and Heterodox Economics (2003-2004), the Social Anthropology Research Unit (2005-2006), and the Department of Economics (2005-2010). He served as a Lecturer (2010-2012) and currently serves as an Assistant Professor of Economics (2012-present) for the Department of Socioeconomics at the Vienna University of Economics and Business. He also serves as a Post-Doctoral Researcher at Institute for Multi-Level Governance and Development (2012-present). During this time, he has been the project head of two different research grants, won four major academic awards for his work in the field of economics, has served as a referee for various academic journals (2012-present), is a jury member for the International Egon Matzner Award for Socioeconomics (2013-present), and has authored two books, numerous peer-reviewed papers, book sections and chapters.

Dr. Fellner completed one year of breathing training based on the work of Ilse Middendorf where he studied the phenomenology of breathing (2008-2009). He completed five years of training with the Austrian Association of Breathworkers where he completed the Breathing Teacher and Breathing Therapist Training program (2009-2014) which included Rebirthing, Conscious Connected Breathing, humanistic psychology, and various types of bodywork. He has also attended many other workshops where he has learned about other breathing approaches such as Mindfulness Training and Holistic Breathwork.

Dr. Fellner earned his certification as a Breathing Behavior Analyst (2017-2018) from the Professional School of Behavioral Health Sciences with distinction. Based on his outstanding work with the Professional School, his exceptional analytical thinking and teaching skills, and his training and experience in the field of breathwork (2008-present), Dr. Fellner was invited to become a member of the certification program faculty of the Professional School (2018) and is now teaching the Certified Breathing Behavior Analyst program in German. He also serves as a Member of the Science and Research Group of the International Breathwork Federation (IBF).