Berthold Gunster (1959) is the founder of the Omdenken philosophy. After studying at the Theatre Academy in Utrecht he worked as a theatre director and writer for years. He also created projects like Not Your Mama’s Bus tour with homeless people in Chicago and Why Is Stas Addicted in Ukraine. Since 2001 he and his team have been offering trainings, workshops and shows about Omdenken to companies and individuals. Berthold wrote thirteen bestsellers about the Omdenken theory.