Sir Paul McCartney knows he can't perform forever.

The 71-year-old Beatles legend has previously spoken of his desire to keep working but knows there may come a time when it becomes impossibly to undertake gruelling tours, and plans to reassess his life after his next run of shows.

He said: ''We're gonna make a little forward roll with this album and tour. And when I come out of that forward roll I'll have a look and see what the scenery is and if there's a cliff I might do a backflip. But I'll decide when I come to it.

''If you ask me what the long range forecast is, I see myself doing what I do forever, but, like a footballer, there has to come a physical point where you might not be able to do it.''

Paul hopes that point never comes because he can't bear the thought of doing nothing with his days.

He told NME magazine: ''I'm expecting myself to get knackered but I'm not. So I'm not knocking it. I'm not even gonna think about it.

''I see people who are younger than me who sit in front of the TV all day. It's like - yeah, alright. I'm not sure that's the life I want. I can think of something better than that.''