Sir Cliff Richard has admitted he still worries about selling tickets to his shows, ahead of his 75th birthday tour.
The singer, who will play at eight venues around the country before performing a six-night stint at the Royal Albert Hall, said that he "still wonders if anybody's going to show up".
In an interview with BBC Radio 2's Paul O'Grady, Sir Cliff said: "When you start your career you have no concept about longevity, for me you don't know what's going to happen, so how it's gone on I've no idea.
"I'm just really grateful that it has gone on and if people want to see me, I like performing so it's no great hassle for me to come out on tour. I like it."
The 74-year-old has already played 32 sold-out concerts at the Royal Albert Hall, where he will perform again on his birthday in October.
He told O'Grady that he has "invited a whole bunch of people", including showbiz friends, to the gig despite usually trying not to work on his birthday.
"I'm just going to work on my birthday and normally I try not to do a concert actually on my birthday but this time I thought what the heck, you know, I'm 75 and so I'll do my birthday night there.
"I've never tried to hide my age anyway and this year, apart from telling everybody I'm 75, you know I've got an album coming out and it's called 75 At 75 because they're putting 75 tracks on this record package."
He added: "I have to sing certain songs, there are some songs I've sung right through from the early 60s, I have to do The Young Ones, I have to do Summer Holiday, I have to do Living Doll, of course I have to do Devil Woman, We Don't Talk Anymore and those sort of things.
"And every now and then, I'm going to stick one new song in that I've recorded for my next album that probably won't come out until next year and that's the volume two of my rock and roll songbook series, I hope it's going to be, and on that album I've done some classic rock and roll, I've done three Chuck Berry songs, a Little Richard song, Jerry Lewis, Phil Everly."
His 75th Birthday Tour starts in Killarney, Ireland, on September 26.