Perhaps you should try some spelling variations:
massiv » massive
passiver » passive, passiven, passively
aktivierende » aktivieren, motivierende, praktizierende
aktivierenden » aktivierenn, motivierenden, praktizierenden, aktivieren, motivierende

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: ((massiv OR passiver) OR (aktivierende OR aktivierenden)).
• Adding a wildcard symbol may retrieve word variants: ((massiv or passiver) or (aktivierende or aktivierenden))*.