However, England's all-time leading scorer has found the back of the net eight times in 14 appearances for club and country so far.
"I have been playing football a long time and for me, it (age) is a number," Rooney told reporters ahead of Wednesday's Champions League clash with Spartak Moscow.
"In terms of me and football, I still feel I am young enough, and that I have a lot of years ahead of me.
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"I have had no major muscle injuries and us players now have all the support of sports science, and all the other guys to help us in terms of preparation, training and games, so I think it's still a fairly young age and hopefully I have got a lot of years to come."
"I feel fitter and fresher than I ever have done really. I couldn't sit here and say I am going to play five or ten more years, but it's something which I have not even thought about," he added.
With the Red Devils currently on a two-year trophy drought, Rooney, who has won the Premier League five times and the Champions league once with United, says he is desperate to get back to the glory days which the club enjoyed under former manager Alex Ferguson.
"We want to get back to winning trophies, of course. That is why you play football -- to try and be successful, certainly at this club," Rooney said.
"In the last few years we haven't been good enough. There has been a big change in the club over the last few years and it's now starting to settle back down into a good rhythm with what the manager wants from us and we are improving," he added.
(Reporting by Shravanth Vijayakumar in Bengaluru. Editing by Patrick Johnston)
