Rick Warren has revealed he is in constant pain because of an autoimmune disease.

The Purpose Driven Life author said on "The Stetzer Church Leaders Podcast" that he had been battling the disease for the last two and a half years.

He said it was not life-threatening but was "debilitating" and the pain had been "constant".

It has also caused mobility issues and that sometimes just walking up the stairs has been "brutal". 

Sharing his frustrations, Warren said that sometimes his hands are "so tight" that he cannot open a packet of sugar or turn the pepper shaker.

"It leaves all my major muscles in pain, pretty much 24 hours a day," he said.

"It's debilitating. It's tough walking, working. But it hasn't changed the way that I think.

"The problem is sometimes I feel like I am this brain on fire, and I'm like in a wheelchair. I'm not in a wheelchair, but the bottom line is it's difficult to move around."

Warren retired last year as the pastor of Saddleback Church, one of the biggest churches in the US. Now he leads the mission-focused Finishing the Task Coalition and has just authored a new book called Created to Dream.

He admitted that the disease had made his ministry work more difficult but that God was "faithful". 

"When I first took this role that God was calling me to lead the Finishing the Task Coalition, ... I thought it made sense that God would call me to do this because I'm not afraid of complexity ... But when I began to look and see how difficult it was with the pain I've been going through, I realized God said, 'I didn't choose you for your experience. I didn't choose you for your years of skills that you've developed ... I chose you because I knew you would trust me even in pain," he said.