 -- Dan Reynolds is opening up about his struggle with ankylosing spondylitis, or AS, a chronic inflammatory condition that causes harsh pain, and, in severe cases, spinal fusion.

The Imagine Dragons frontman is hosting an online talk show called "This AS Life Live!," during which he'll speak with others who've been diagnosed with the disease and discuss how they've lived their life with AS.

Reynolds was diagnosed with AS at around age 21, right about the time Imagine Dragons were starting to take off. Reynolds says there were nights when he had to stand completely still on stage because of the pain.

"Suddenly, this was my moment to really...the band was starting to take off, and I thought it's all gonna fall apart, because now my health is going," Reynolds tells ABC News.

Reynolds has since received proper treatment, and he says now he's "in remission," though he experiences flare-ups from time to time. Still, he long felt hesitant about sharing his condition publicly, but as he's grown older -- he's now married with one daughter and twins on the way -- Reynolds feels he has a responsibility to raise awareness about AS.

"I just felt like I needed to speak out, and say, listen, this is something I deal with," Reynolds says. "Having a disease does not make you weak, it's not something to be ashamed of. It can be your greatest strength, and it has been my greatest strength. I really believe a lot of the passion in the music...I know a lot of the passion in the music has come from struggling."

For more info, visit ThisAFLife.com