Ireland's Fittest Family returns for a fifth series on Sunday nights to make you feel good about yourself watching others struggle in the mud while you have your feet up in front of the fire. Host Mairead Ronan is joined by coaches Anna Geary, Davy Fitz, Derval O’Rourke and first time Fittest Family coach and rugby legend Donncha O’Callaghan. The foursome will be putting twelve new families through their paces with a selection of new obstacles and terrains that are sure to be even more taxing than previous seasons. Tonight's episode sees the first six families face a series of gruelling physical challenges in the underground tunnels of a 400-year-old fort in Crosshaven, Co Cork.