Stefan started out as photographer and musician in 1983. He went into advertising in 1988 as copywriter at Hildmann, Simon, Rempen & Schmitz/SMS where he became creative director in 1992. In 1994, he was one of the founding partners of Rempen & Partner Werbeagentur.
Stefan worked for Aids-Hilfe, Deutsche Post, Holsten, Mazda, Microsoft, Nikon, Peacock, Redge Grundy, Ritter Sport, RWE, Siemens and Virgin Records.