The 32-year-old keeper - who also skippers Spain, leading the country to their FIFA World Cup and double UEFA European Championship successes - is regarded as a club legend at Real having spent the entirety of his illustrious career there.
However, Casillas made just 19 La Liga appearances for the club last season and is yet to play in the Spanish top flight this term, as Diego Lopez is preferred for league games under Real boss Carlo Ancelotti - as he was by the Italian's predecessor Jose Mourinho.
Casillas is established as Real's first choice in both UEFA Champions League and Copa del Rey fixtures, but admits he wants to play more often so could seek pastures new over the coming years.
He told Melodia FM: "Playing for Real Madrid from such a young age means people are constantly talking about you.
"And with social media that's even more the case. It's a big responsibility and I try to do things as best I can. You have to try to be calm and collected.
"I'm thinking more and more about what I'll do when I quit playing. I'd like to stay involved in football and help the club, if the circumstances allow it.
"I can play on until I'm 40. If you look after yourself as a goalkeeper, you can carry on until that age.
"I'd love to be able to keep playing for Real Madrid until I'm 40, but a time will come when that's not possible. I'll consider my future at Real when my contract expires."
