King Charles III celebrated his 78th birthday with an appearance on Elton John's Apple Music radio show, "Rocket Hour," where the two joked about aging and reflected on their decades-long friendship.

The king, who turned 78 on Saturday, joined the legendary musician for a prerecorded episode celebrating the 50th anniversary of The King's Trust, the charity Charles founded in 1976 to support young people.

During the episode, Charles reflected on John's performance of his hit song "I'm Still Standing" at a 1986 concert marking the charity's 10th anniversary.