"Last year was a quite an eye opener," he told BBC Radio 2. "I was like, 'Who am I without Wembley Stadium saying, 'you're awesome'?"
"I'm trying in my life right now to not attach too much to being a pop star. I'm trying not to get my self worth from external validation."
He was speaking as Coldplay unveiled their new single, Higher Power.
They premiered the 80s-inspired pop song on board the International Space Station overnight - teaming up with French astronaut Thomas Pesquet, who beamed the music back to Earth by satellite.
In a video chat, Chris Martin told the 43-year-old aerospace engineer: "Right now we aren't able to play for anybody on Earth, so we thought we'd just play for you. It's like our one-man concert."
The singer later told Zoe Ball the song had similarly intergalactic origins: "We've been trying to imagine what music might sound like on other planets, and try to imagine being those other acts, so we're not thinking of ourselves as being the band Coldplay from England," he explained.
He came up with the title first, but struggled to find the melody and lyrics to go with it.
"Then one day I was staying in this place and the sink was very resonant," he said. "And so I started hitting the sink [to make] this beat... and then I went to the piano keyboard, and the song just landed in one go."
"So thank you to that sink," the singer added. "That's great plumbing."
Higher Power is the band's first ever collaboration with Swedish hitmaking powerhouse Max Martin, who has previously topped the charts with artists like Britney Spears, Taylor Swift, Justin Timberlake, Ariana Grande and The Weeknd.
"We know that he's far more successful than we are, so it's quite humbling," Chris Martin told Zoe Ball.
The producer forced the band to "raise our game" in the studio, he admitted.
"I had to audition songs for him. [We] got really back to basics."
"It's been interesting to let someone right into the fabric of the songs [and] to suggest things that no one else has ever been allowed to suggest."