Imagine Dragons Singer Dan Reynolds Shows off Incredible Body Transformation

Imagine Dragons frontman Dan Reynolds recently took to Instagram to show off the results of some important lifestyle changes.

Reynolds posted a photo of himself on Sunday performing onstage and showing off his muscular physique.

"I've spent a decade fighting an auto immune disease that inflamed all my joints (AS)," Reynolds wrote. "I now live pain free, am in full remission and am the healthiest I've ever been. I owe it to this man [Brad Feinberg] Correct diet, vitamins and exercise. I'll share it all with you soon. It's been life changing for me."

A day later he posted before and after images showing just how much his body had changed.

"Just a few months of reworking my entire lifestyle/diet/exercise [with] [Brad Feinberg] and I have zero inflammation now," Reynolds typed. "These before and after pictures say it all. Sorry for the corny exercise post but truly changed my life and healed years of pain. Unbelievably grateful for health."

Reynolds went into detail about his struggles with AS (Ankylosing spondylitis) in an interview with PEOPLE back in 2016, saying the pain first began in his back when he was 21 years old and that he'd kept it a secret for years.

"It was beyond the pain that you feel when it's just a back ache. It felt like someone was drilling my nerves," he recalled to PEOPLE. "It was right when the band was starting to have minor success — we were starting to sell out small clubs, and we were playing these very active shows and it started to make me have to cancel shows."

"I couldn't get on stage," he added. "I couldn't move, I couldn't sleep at night, I couldn't perform without standing perfectly still. I couldn't sit down for more than a half an hour."

After revealing his issues with AS, Reynolds announced he was partnering up with the Spondylitis Association of America and Novartis to create the This AS Life Live! project, an online talk show where people with AS are brought on and talk to Reynolds about their experiences and how they've overcome it.

Back in April, Reynolds announced he and wife Aja Volkman had separated after seven years of marriage.

"After 7 beautiful years together, Aja and I's marriage has come to an end," he wrote at the time in a series of tweets. "Our children continue to be the most important thing in our lives, & we will continue to co-parent them with all our love. I ask that you please respect our privacy at this time as we work through this as a family."

The couple have three daughters together — Arrow, 5, and twins Coco and Gia, 1.

Photo credit: Desiree Navarro / Getty Images