The 40-year old Australian goalkeeper's future at Craven Cottage is in doubt with his contract set to expire at the end of the season and he insists he will move on provided the Southwest London club do not want him any longer.
"I'd find it difficult to be paid and not play, simple as that," he told SunSport.
"It's not about money, it's about wanting to play every week.
"If I am not performing well and someone comes along and plays in your place, I have no problem with that.
"But you know when the signs are there. You know if your future is in doubt - you see it coming.
"If we go our different ways, I'd like to be told if I'm not good enough."