In an interview on ITV's This Morning, the singer confessed that he had allowed the huge success of his hit track 'Mandy' to turn him into a "jerk".
"When 'Mandy' hit number one everything changed and I became a jerk I think," he said. "When I look back I didn't like who I was and I didn't know how to pull myself back together again, until one evening I looked up and everyone around me I was paying - all my friends had disappeared... so I stopped it and went back to being a real person.
"But it [was] this fame and success thing that knocked me over like a hurricane and I say a little prayer for the people that are younger than I was."
He added: "I hope Justin Bieber has a good family unit because that will help."
The 67-year-old told Phillip Schofield and Holly Willoughby that the success of 'Mandy' in 1974 had come as a "big surprise".
"I never wanted to be a performer," he said. "I never thought about singing so when this hit it was something out of the blue."