Sir Paul McCartney is ''very happy'' with his ''trucker'' wife.

The 75-year-old singer couldn't be happier with his spouse, transport heiress NANCY SHEVELL - who he wed in 2011 - and is proud of her career achievements.

He gushed: ''Nancy's very impressive. She is a businesswoman, she still runs her dad's trucking company with 4000 trucks.

''She's a trucker. She's used to men's humour. She's a beautiful, smart and funny girl. She loves music ... We're very happy together.''

The Beatles legend admits he is often blown away when he reflects on his own success as a member of the biggest group of all time.

He told Australia's Daily Telegraph's Stellar magazine: ''I do sometimes think, 'Wait a minute! I was one of The Beatles! Can you believe that?'

''I was one half of the Lennon/McCartney songwriting team!

''Occasionally these things occur to me. Normally it's just something I take for granted, but sometimes I look at it and think, 'Bloody hell, it's amazing.' Then I get right off it before my head explodes.''

Despite his advancing years, Paul - who has four adult children with late wife Linda and 13-year-old Beatrice with second spouse Heather Mills - tries not to worry too much about his mortality and just wants to continue having a good time.

He said: ''When I was a kid I'd look at someone who was 75 and think, 'Bloody hell, that's old'.

''But you get to 40 and you think, '40, that's old.' Then you get to 50 and think, 'Well, 40 wasn't so old.' As you go on you look at the decade before and think, 'I thought I was old then, but I wasn't.' Now you look at people the decade ahead of you and think, 'Well, he's still pretty cool.'

''I enjoy very much what I do: I feel healthy, I'm having a good time, making a new record, going on tour. It's my dream come true. It's what I always wanted to do when I was a kid. I'm still allowed to do it, so I'm not complaining.

''I belong to the group who think age is just a number. As you get to my age you're inevitably aware of your mortality and you start thinking, 'What does that mean to my kids and my grandchildren?' But I've always taken the same attitude: when my time is up, that's it. Until then, I'm going to have a laugh.''