Sir Paul McCartney sometimes has to remind himself to concentrate on stage as he drifts off.

The former The Beatles legend loves performing for his fans and still enjoys singing the iconic songs which made him famous. However, as they are so familiar to him he occasionally realises he isn"t paying as much attention as he should be.

"Don"t ask," he replied, after admitting he sometimes thinks about strange things on stage. "It"s scary, because sometimes I suddenly wake up in the middle of a show and think, "Concentrate man! Come on, you"ve got an audience here!""

Many other stars of the 70-year-old"s era admit they tire of performing the same tracks over and over again. Paul sees that as a way to relive his youth and is often amazed by how talented he was at such a young age.

"I do enjoy them! One of the great things now is that I"m reviewing them every time I sing them," he told Q magazine, when asked about some of The Beatles" classics.

"I"m looking at myself now, singing it, but thinking of myself then, writing it. It"s like time travel. Singing Eleanor Rigby and thinking, "Keeping her face in a jar by the door," that"s a pretty cool turn of phrase. But some of the other things going on in my mind are nobody"s business."