Image copyright Mike Posner Image caption The star walked nearly 3,000 miles in six months

US singer Mike Posner is best known for the song I Took A Pill In Ibiza, which spent four weeks at number one in 2016.

But after losing his father to cancer two years ago, the star gave up his old habits, disavowing drink and drugs, and embarking on a life-changing journey.

On 15 April this year, he started walking in Asbury Park, New Jersey; and didn't stop until he reached the Pacific Ocean, six months later.

"I walked to become someone I'm actually proud of," he tells the BBC.

"Before I left, I suspected I had a little pocket of untapped potential inside me," he says. "I was wrong, there was a huge basin of untapped potential."

The star's journey is documented in the video for his new single, Live Before I Die, a collaboration with British producer Naughty Boy.

Posner covered 2,851 miles (4,588km) on his trek, rising at 4am every morning, and sometimes walking 30 miles a day.

Along the way, he was bitten by a rattlesnake and had to be air-lifted to hospital in Colorado, where he was told he might lose his leg. Amazingly, he resumed his expedition just three weeks later, in the exact spot where he left off.

Image copyright Mike Posner Image caption Posner had to learn to walk unaided after taking the anti-venom

But the "hardest day" came three months into the walk, after floods in Missouri forced him to change his route - meaning a two-day detour in the "wrong direction" to reach the border with Kansas.

"I kept saying to myself, 'Just get to Kansas,' and that was fine... Until I actually got to Kansas. Because I'd created this false finish line in my head, my brain thought I was done when I wasn't even halfway."

The prospect of getting up and walking again the next day after crossing that imaginary "finish line" took a toll on his health.

"My body was really starting to fall apart," he recalls. "If I didn't consciously focus on taking the next step, my body would stop. And I was so tired that my default was stop."

But Posner stuck to his mantra - "keep going". For the rest of the 186-day trip, he visualised his goals in terms of "checkpoints", not finish lines.

As he continued, and his beard got bushier, Posner grew stronger and more accustomed to the discomfort. He developed a dislike for cities and suburbs; which made him feel claustrophobic "after being under the stars and in the desert" in Nevada and Colorado.

Mum's concern

But the highlight was his 10-day hike across the Navajo Nation - the American Indian territory that spreads across Arizona, Utah and New Mexico.

The Diné people showed Posner a "kindness and compassion that you won't believe", bestowing him with a sacred eagle feather, and making him reassess his relationship with the land.

As if the challenge wasn't enough on its own, the 31-year-old kept working on music during the journey, releasing a new song every time he crossed a state border.

When he reached his final destination, he dropped a mixtape - also called Keep Going - including several interludes where the likes of Diddy and Aerosmith's Steven Tyler left words of encouragement on his voicemail.

The final message came from his (extremely) concerned mum who advised, "You can stop doing this if you want, if it's too hard or you decide it's too much.

"I think you're going to be shocked at how difficult it is, but I love you for trying it."

Posner's pilgrimage ended on 18 October, as he plunged into the Pacific Ocean at Venice Beach, California, cheered on by fans and supporters.

But after giving up all of his vices, how did he celebrate?

"I went to bed. Woke up at 4am. Hit the boxing gym," says the star.

"It sounds crazy because my body was so broken and tired from all those miles but I needed to let my body and mind know that even though The Walk is over, we aren't done."

"Now 'The Walk' is over but it's my job to keep exploring what's there."

Image copyright Universal Music Image caption Posner collaborated with platinum-selling British producer Naughty Boy for his new single

Posner's epic journey inspired his new song, Live Before I Die - an uplifting, emotional pop track that sums up his personal transformation.

"I stopped smoking weed a year ago / Maybe I'm less cool now, I don't know / But I got two more albums done / Instead of sitting there all stoned / Yeah, I stopped smoking weed a year ago," sings the star over a nimble guitar hook.

"It's the most heartfelt and real song, it affects me and my core," says producer Naughty Boy, whose own mother has been affected by health problems in recent years.

"After seeing the video, it's almost as if Mike walked for everyone and it feels like now is the time for all of us."

Meanwhile, Posner hasn't stopped challenging himself. In the past week, he's climbed two mountains - Oregon's Mount Hood and Washington's Mount Adams - with a combined height of more than 7,000 metres.

So what's next?

"I have many ideas but no plans," he says with a wink. "I'm in the process of deciding what to do next. Right now I'm just rehabbing my body and working on a few secret things..."

Image copyright Mike Posner Image caption Posner says more challenges are on the way

Naughty Boy and Mike Posner's Live Before I Die is out now.

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