Born in South Australia, Dr. Hewlett trained at Royal Adelaide Hospital in South Australia as a Resident Medical officer.  He trained as a Senior Resident Medical officer with the Department of Internal Medicine, Repatriation General Hospital and as Medical Registrar at Royal Adelaide Hospital, Department  of  Internal  Medicine  and  Subspecialties.    At  the   University  of   Southern   California,

Dr. Hewlett trained as a Barlow Fellow in Pulmonary Diseases and then served as Senior Clinical Pulmonary Fellow at the University of Colorado Medical Center.  Dr. Hewlett received Board Certification in Internal Medicine in 1977 and in Pulmonary Diseases in 1978.