Christensen worked as an ironmonger from 1971 to 1976, before joining the Queen's Lifeguard Regiment as a Junior NCO (1976-90). During his service, he was a senior shop steward and member of the National Executive of HKKF trade union for non-commissioned army personnel.
He was Vice-Chairman of the Danish TUC in Brovst (1984-1988), and Chairman of Brovst constituency organisation (1984-1989). He then served as a member of Brovst town council (1989-2004), including terms of office as Mayor (1998-2002) and Deputy Mayor (2002-2004).
Having matriculated at the Aalborg School of Commerce in 1979, and graduated Bachelor of Commerce in 1984, he qualified and worked as an instructor at Aalborg Training School in 1990 before becoming a business consultant with Aalborg Trade Council (1992-98). He has been involved in various other trade union and local government organizations in North Jutland.