Growing up in the neighbourhoods of Carabanchel and Estrella, he was surrounded and influenced by theatre, literature, and art from an early age, and this guided his academic pursuits and eventual career.

In 1984, thanks to a scholarship obtained by his mother, Mañas moved to live with his family in New York City and studied at the Actors Studio.

He worked with various prestigious directors, including Adolfo Aristarain, Carlos Saura, Ridley Scott, Manuel Gutiérrez Aragón, José Luis Cuerda, and Jorge Grau.

In 1997, he wrote, directed, and produced his third and last short, Paraísos Artificiales (Artificial Paradises), which also won important national and international awards.

A year later, French television channel Canal Plus invited Mañas to direct a documentary on the peace process in Northern Ireland.