Our no.7 is the Reds' leading goalscorer this term but missed the Emirates FA Cup win over Aston Villa on Monday night due to a minor injury.
At 36, he believes he still has plenty of years at the top because he feels, genetically, he is much younger and is supported by his famed long-term fitness regime.
However, he stresses the mental side of things is becoming more and more crucial in enabling him to compete with younger opponents.
"I feel happy to be a player who has shown who, in my case, longevity has been a crucial factor for me to keep playing at a high level, putting in good performances," he told ESPN.