John Legend suffered "a lot of rejection" as a young musician.
The Grammy-winning star is one of the best-selling artists in the world - but John admits that his journey to stardom hasn't been straightforward.
He explained: "There was a lot of rejection. But if I'd got a record deal at 18, I would have screwed it up.
"I didn't know what went into being a successful solo artist. I just thought, 'Oh, I can sing and I'm writing some decent songs,' but there's more to it than that."
John, 43, stars on the US version of 'The Voice', and that experience has caused him to reflect on his early days in the music business.
He told the BBC: "I'm a coach on 'The Voice' now and that's something I'm always thinking about when I'm advising the artists.
"They're all really good singers - some of them are much better singers than I am - but the only way for them to make it is to have a point of view that's interesting and distinct and personal.
"Music is not just a virtuosity competition."
John actually spent three years working as a management consultant, as he struggled to get his music career off the ground.
However, that experience taught him some important life lessons.
He said: "It's a demanding job, they expect you to work a decent number of hours, but I was living a double life, writing at night, gigging at night.
"People always ask me if I get tired now and I'm like, 'I get way more rest than I used to!'"
Meanwhile, John recently revealed that he's "eternally grateful" to Kanye West.
The singer released his debut album, 'Get Lifted', on Kanye's GOOD Music record label, and he'll always appreciate what the rap star has done for him.
John reflected: "I can’t imagine my career without Kanye’s influence. He gave me a platform because of his success as an artist and producer.
"I don’t know whether any of this would have happened without us meeting and helping each other. I’m eternally grateful to him."