The 28-year-old England international has failed to deliver in major tournaments since he impressed as a teenager at the 2004 European Championships.
The striker's World Cup campaigns in 2006 and 2010 were marred by injuries, while his form at Euro 2012 was halted after missing the first two games because of suspension.
"For me personally, I feel the World Cup in 2018, I'll be a bit older then so it will obviously be difficult to impact that the way I believe I can do," Rooney told reporters.
"I feel this is the really last big one that I feel will probably get the best out of me. I feel ready, fresh and as good as I can do to go into this tournament. This is the one where I have to show what I can do.
"I believe I am in the best possible shape and the best condition I can be in to do that. I am ready for it. I am excited for it. There will be no excuses this time if I don't perform. I certainly won't be looking for any excuses this time."
England, who are currently at a warm-weather training camp in Portugal, will begin their World Cup campaign against Italy in Manaus on June 14.