King Charles and Sir Elton John joked about the problems of ageing as the pair joined for a special radio show to coincide with the monarch's 78th birthday.
Sir Elton, 79, was joined on his regular Rocket Hour radio show for a special episode during which the King shared his musical memories as the pair chose 14 songs together.
The programme also marked the 50th anniversary of the King's Trust and highlighted how musicians have supported the charity's efforts.
"We and the Trust are definitely still standing," the King said, as he highlighted Sir Elton's track I'm Still Standing as one of his favourites because of the song's "message of resilience".
The music legend joked in reply: "I'm still sitting now, though" giving a large laugh, with the King chuckling: "With occasional bits dropping off here and there. I know this is a terrible problem as we get older."
The special was recorded last month at Apple Music Studios in south London and premiered on Saturday morning.
The King recalled Sir Elton's 1986 performance at Wembley Arena, which marked the charity's 10th anniversary.
"I suspect that no-one who was present on that night in 1986 could possibly forget your performance of I'm Still Standing," King Charles said.