Fien Callens has coached the U18 teams of the 'Yellow Tigers' for a few years now, leading them to a silver (2013) and a bronze (2014) at the Western European Volleyball Zonal Association Youth Championships. She also coached the team to 1st place at the 2015 European Championship Qualification Tournament and to 3rd place at the 2015 Girls U18 Volleyball European Championship.
In addition to the National Team, Callens is also a coach at the Top Sport School in Vilvoorde.
As a player, Fien Callens twice won a Belgian Cup, in 2009 with VDK Gent Dames and in 2013 with VC Oudegem. She has also excelled on the beach, winning the Belgian Beach Volleyball Championship in 2013 (as well as claiming bronze medals in 2012 and 2014).