Bellamy, 30, said: "If we get into the Champions League, which we are all trying to do, and I'm still a very big part of that, then I have to be realistic.
"Can I compete in the Champions League, Premier League and every day do battle to fight for my place in the team? Would I be able to play 60 games a season?
"Probably not. I know if my knee is sore one week then realistically playing a friendly in Australia on a Wednesday, for example, may not work out for me."