As a marina professional and a certified marina operator, Holzem learned from his educational experiences, as well as from managing different marinas including South Bay Marina in Green Bay, Wisconsin. He works at Kewaunee City Marina on Lake Michigan. His marina experiences taught him to understand the different needs and wants of the boating public and conclude that a hospitality approach to marina management increases customer retention. Holzem has presented this topic at the International Marina & Boatyard Conference and International Boatbuilders Exhibition & Conference.