RK on MUTV:
``All you can do is keep working hard with the medical people and keep listening to them.
``You have keep your head down and hope eventually there will be light at the end of the tunnel.
``I have come back in and am really enjoying it. It is great to be back playing with the lads.''
United face a crucial spell at home and abroad with the Champions League re-starting next month.
Manager Sir Alex Ferguson has been unable to strengthen his squad during the transfer window but Keane is comforted by the knowledge there is healthy competition for places.
Keane said: ``All good teams in Europe need big squads. You need to change it every now and again and freshen things up.
``When you get to January-February time, players can get tired. Players are also going to get injured, players are going to get suspended.
``I feel great since I've come back. If you can't enjoy the big games and must-win situations you might as well give up. That is why I came to Manchester United.''