Marin got his PhD at the Faculty of Kinesiology of the University of Zagreb, during his graduate studies at the same university he chose the field of fitness training of athletes. His many years of work experience began during his student days, when he was a strength and conditioning coach at the Football club Zagreb,  Basketball club Zagreb, the youth teams in the Croatian Basketball Federation, and was a member of the Croatian national football team’s coaching staff at the 2022 World Cup in Qatar. He has been part of the Biotrening team for 10 years and specializes in the individual fitness preparation of football players and can boast of having worked with more than 40 athletes at the local and international level, some of whom are current and former national team members in their countries. Likewise, he is a lecturer at the Faculty of Kinesiology in Zagreb on the subject of fitness training of athletes, the Croatian Football Academy on the subject Theory and training methodology, and the Lavoslav Ružička Polytechnic in Vukovar on the subject of physiotherapy. He is the author of 20 professional and scientific works related to the fitness preparation of athletes, and in this way he tries to combine sports science and practice.