Tom Hanks became audibly emotional as he described the loneliness of his "vagabond" childhood on Desert Island Discs.
He had to pause to collect himself as he discussed the impact of hearing one of his music choices, Strauss' Also Sprach Zarathustra, the theme to 2001: A Space Odyssey, on him as a teenager, after a nomadic childhood with his chef father Amos, living in 10 houses in five years.
He told host Kirsty Young: "This was the 'Wow' moment of my life going from kid trying to figure out what's interesting in this life to young man yearning to be an artist.
"I started asking myself... how do I find the vocabulary for what's rattling around in my head? Not long after I started going to the American Conservatory Theatre by myself to see plays I had no idea even existed."
Asked by Kirsty what those feelings in his head were, Tom took a long pause and appeared to wipe tears from his eyes.
"What have you done to me?" he asked an apologetic Young.
"No, it's all right, because I put too much thought into this list. What it was, it was the vocabulary of loneliness," he replied.
The Cast Away actor, 59, admitted that his first marriage at 21 to actress Samantha Lewes, which produced children Colin and Elizabeth, had been to "quell the loneliness".
He continued: "Having a kid at 21 was the greatest thing that ever happened to me because I didn't smoke pot. I didn't do drugs, I was not a party boy."
It meant that by 27 years old, when he met his second wife, actress Rita Wilson, whom he married in 1988, "you end up meeting that other person that you're like, 'She gets it'.
"I don't think I'll ever be lonely any more, that's how I felt when I met my wife."
Tom picked Talking Heads' Once In A Lifetime in tribute to his first date with Wilson at the band's movie.
Memories of sharing a room with his brother and father as a seven-year-old and seeking a place where "I won't be alone, I won't be lonely, instead I'll feel content" made him pick Beatles track There's A Place as another choice.
Among other topics, Tom made Kirsty laugh as he explained his indelicate re-writing of the script of Sleepless In Seattle, where he plays a widower whose son tries to find him a new wife.
In a scene where his son does not want him to leave for a romantic break with his new girlfriend, Tom said the original script had his character "flummoxed by this crisis".
"I said (to writers Nora and Delia Ephron), 'You guys are out of your mind. You know what a dad would say: 'Hey kid, I'm going away for the week because I want to get laid.'
"We put a version of that in the movie."
Tom's Desert Island Discs can be heard on BBC Radio 4 on May 8 at 11.15am.