In his student days, Härenstam would play in small local plays, and started to work closely with a fellow student Lars "Brasse" Brännström. Their partnership would be known across Sweden in 70's and up till the mid 80's where they here Sweden's most popular comic duo. They would play side by side in both movies and TV shows. In 2005 he teamed up with his old partner for a theater comedy play Muntergökarna.