The Portuguese superstar only signed a four-year contract with current club Juventus last summer following his £100 million transfer.
And despite the five-time Ballon D'or winner helping Juve to the Serie A title last season, he admitted it may be time to call it a day.
Ronaldo told TV1: "I don't think about that.
"Maybe I can leave my career next year … but I can also play up to 40 or 41.
"I don't know. What I always say is to enjoy the moment. The gift is excellent and I have to continue to enjoy it."
Ronaldo finished as Juve's top scorer last season with 21 goals in the league which were crucial in the Old Lady's defence of their crown.