With a career spanning two decades and sales in excess of 45 million records, Usher is one of the most successful singers in the world, but as his new album reveals, he is still seeking contentment.
"Evolve or evaporate".
It is one of Usher's favourite phrases; a mission statement that has shaped his career, from gospel choir-boy to R&B sex object.
He has been in the public eye since he was 14, making one of his first TV appearances as "one to watch" on the Oprah Winfrey show, alongside Venus Williams and Katherine Heigl.
"Isn't that incredible?" he asks, "she did a really good job predicting that."
"I was living as a dreamer then, but I'm living the dream now. It happened. It happened as a result of hard work."
The star is in a reflective mood as he releases his seventh studio album, Looking 4 Myself.
"I listened to all of my old albums before making this one," he says.
"I put storyboards up right around me as I was writing, and I found different points of my life when I felt true passion, and I wrote about all of that."
Lyrically, that means battling some big demons.
On Sins Of My Father, the 33-year-old talks about how his father abandoned him as a child and the knock-on effect that has had on his own relationships.
"I don't deserve the debt that came with my birth," he sings on the track.
Elsewhere, the star addresses the fall-out of his divorce from Tameka Foster, the mother of his two children.
"I lost an incredible relationship because I had a passion and it was music," he says.
Even a track like Numb, which appears to be an archetypal forget-your-worries party anthem, has deeper roots.
Usher says the song is about an attempt to "help someone who couldn't help themselves", a situation that left him stressed out and numb.
"I almost killed myself trying to help this person," he says. "In the end, I went, 'man I don't care any more, I'm letting it go'.
"As a result I felt free for the first time."
If the lyrics find Usher dwelling on his past, the music propels him into the future.
Never known for his humility, Usher has called his new sound "highly-anticipated" and "revolutionary".
He has even compared himself, remarkably, to Picasso in his blue period.
In truth, minds will probably remain unblown.
Usher's sonic reinvention is hardly a million miles away from Ne-Yo, or Rihanna, or any of the other R&B artists who have incorporated euphoric house beats on their recent hits.
"It may sound similar to other things, but the difference is the essence of soul in it," he says.
"Max Martin [Britney Spears' producer] and David Guetta were the two people who made me understand how using dance music in this way, by putting soulful melodies on top of it, could work.
"That's not what you get from listening to other dance records."
When the singer does push at the edges of modern R&B, he produces some of the album's best songs.
Climax - the looping, claustrophobic debut single - features Usher's most death-defying falsetto to date.
And the album's cheeky opening track reworks a Billy Joel hook as a rasping synth riff.
"That song was a classic," Usher beams, breaking unprompted into Uptown Girl's chorus.
"I use it as a song that will bring everyone together, feeling good. It speaks to a very wide demographic, both old and young, and we made it fun.
He says the idea to "borrow" Joel's 1983 single came from producer will.i.am.
"It was silly," he says, "but Will's approach is always that way - 'don't take it too serious, have a good time, joke on it'."
Looking 4 Myself was launched with a one-off show at London's Hammersmith Apollo on Monday.
Taking to the stage in a tangerine leather jacket and tartan trousers, Usher ran through two decades of hits, proudly declaring: "18 years, y'all".
The gig something of a homecoming. Usher last played the venue at the start of his recording career, after scoring his first ever number one in the UK.
"It felt incredible to be received outside America," he says.
"In those days there was no online, so having a hit record abroad was a big deal and a number one record was a big, big deal."
Monday's concert was streamed live online, and the stage was decorated with tweets from fans watching the show all around the world.
They ranged from the mundane ("Go on Usher") to the depressingly mundane ("Usheerrrrrr! Bayyybeeeee!").
The audience inside the venue was infinitely more fascinating. Not only did they know every word to every song, but many could replicate the intricate, limb-popping dance routines.
"I saw that, yeah," grins Usher.
"I have a motivated fan. A fan that wants to move, that likes to dance. Nine times out of 10, they will work out listening to my music."
"When I'm performing, I actually have microphones in the audience so I can hear what they're saying and get their feedback."
You have to wonder what Usher heard through his earpiece during the concerts slower numbers, which triggered a tsunami of snogging.
Has he ever been told his music is responsible for babies being conceived?
"I've heard that a couple of times," he says with a mischievous twinkle in his eye, "and I certainly know of one... my son."
Looking 4 Myself is out now on RCA