The 23-year-old singer - who has rapidly emerged as one of the world's most popular artists - freely acknowledges there's a disconnect between the sadness of his songs and his cheerful personality. Buy tickets below.
He explained: "People say they wish my songs were more like my personality, but then I'd be 'Weird Al' Yankovic.
"I don't want to write a song about being chubby. I don't want to write a song about my pubes.
"I've had the best few years of my life, but in the short periods when things have been bad I've put them into a song. They are more interesting to write about because those moments stick out."
Lewis thinks it's important he remains true to his real-life self whenever he's in the spotlight.
The singer also believes the public would easily be able to see through any insincerity.
He told the Times newspaper: "It's 2020. You can't take yourself too seriously any more because people see through it.
"Can you imagine chucking a TV out of a hotel window today? Everyone would just look at you and say, 'We were watching that, you prat.'"
Lewis' career was transformed by the success of 'Someone You Loved', the hit single he released in 2018.
But Lewis now believes most people are tired of hearing the record.
He said: "I came up with that song and thought, 'People who like my music will love this.'
"But it didn't do much when we first put it out and it felt like I was getting left behind. Slowly it started to pick up steam. Now everyone is sick of it."
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