That's very easy to say from the outside looking in. However, he's 36 and at the end of his international career. He's travelled with the squad and worked bloody hard to try and get himself through the injury he picked up. He's been pretty instrumental in getting Ireland to the tournament. The whole squad (and the country, really) are holding their breath to see if you can play.
The manager, player and medical staff all agree it's touch and go. But he can stand and kick. With painkilling injections, he can play.
He's not perfect, far from it, but the manager asks him to play because, on balance, an unfit Shay Given is still better (at present) than a fit Kieron Westwood in terms of ability and the effect on team morale.
Given is the most senior player in the squad. 120+ caps. He's seen by everyone (except Robbie Keane) as a better leader than Robbie Keane.
His manager asked him to play and you don't say no to playing for your country in an international tournament.