Billy Joel has always "resisted" making documentaries about his career

In an interview with People, Billy said: "I've resisted this kind of thing for so long. I'm sick of talking about myself. Some of the stupid stuff I did, that's painful to talk about. (But) they asked me for some thematic guidance. I said, 'Just tell the truth.'"

The documentary delves into how the Uptown Girl hitmaker has overcome substance abuse, failed marriages and mental health struggles during his lengthy career and Billy found the process "self-revelatory".

The 76-year-old singer - who has daughter Alexa, 39, from his marriage to model Christie Brinkley, as well as Della, nine, and Remy, seven, from his relationship with current spouse Alexis Roderick - said: "There was some stuff I found out about myself. There was some self-revelatory stuff."

Joel admits that he initially just wanted to get the documentary, which features contributions from his family and friends, "over with" as he is so reluctant to talk about himself.

He said: "My goal was to get it over with.

"When I do interviews, people just ask you about yourself and you get a little self-conscious about it eventually. It's almost embarrassing.

"When you're talking about your personal life detached from the material... I suppose there's a little bit of wariness involved."

The We Didn't Start the Fire singer feared that he would "hate" the film as it revisited some of the unhappier times in his life but he didn't feel that way when he watched the finished documentary.

Billy - who has reassured fans he is "okay" after being diagnosed with the treatable brain condition normal pressure hydrocephalus in May, which forced him to cancel his upcoming concerts - explained: "You realise sometimes you were a jerk and you did something stupid or you were wrong, or you were mean and you didn't mean to be. Although I always maintain that the only original thing any of us really does is make mistakes.

"I was worried, maybe I'm going to hate this thing, because it's a lot to ask of somebody, a lifetime of work. (But) at the end, I didn't hate it, which, to me, is the real compliment."