Rick Warren is a man who cares primarily about people's souls but the Purpose Driven author has spent the last few years trying to get his congregation to care about their bodies too, and in his view, the two can't be separated.

It's called the Daniel Plan and the guiding philosophy behind it is that the 5 Fs of faith, fitness, focus, food and friends can all work together with great results for your body and health.

Just like his bestselling Purpose Driven book aims to refocus people in their faith life in 40 days, the Daniel Plan uses the same time frame and challenges Christians to reset their physical lifestyles.

It was launched back in 2011 and in the first year, some 15,000 members of Warren's Saddleback congregation lost a collective 250,000 pounds.

The Daniel Plan also inspired the launch of new "active ministries" at Saddleback, including Walk & Worship bringing together exercise and friendship, and Daniel Plan study groups.

Suffice to say the accompanying book, "The Daniel Plan: 40 Days to a Healthier Life" shot up bestselling lists following its publication last December.

It was co-written with Dr Mark Hyman, of The UltraWellness Center and medical contributor to Katie Couric's TV show, "Katie".

Speaking around the time of the book's launch, Warren said that the Daniel Plan was "far more than a diet".

"It is about living a healthier life based on biblical principles. You can't love if you don't have the energy to love. If you go home every night and lie on the couch because you're exhausted from not eating right and your blood pressure is too high, well, how can you make a difference?" he said.

He's also been upfront about his own need for the Daniel Plan as much as anybody else's. He told Time in an interview that his thinking behind it was: "I'm going to get in shape. Does anybody in the church want to get in shape with me?"

Three years and a book down the line, the Daniel Plan is continuing to prove a hit with Christians serious about keeping themselves in the best shape for God.

Just last weekend, 3,000 people turned up to Saddleback for a Daniel Plan rally where Dr Hyman and others on the team took them through simple exercises they could do from their own seats.

And Dr Hyman was upfront about the faith connection and the value we may or may not be putting on our physical bodies.

"If Jesus came to dinner, what would you feed him?" he said. "Would you give him a Big Mac, fries and a Coke? Would you feed him all the junk that we feed ourselves and our guests when they come to dinner? Or would you eat real food?"

According to the LATimes, Warren has said he is still working on his own personal weight loss goal but has been able to downsize from roomy Hawaiian shirts to more snug-fitting black T-shirts.

"Is this something new? No," he said. "For 2,000 years the church has been caring for the sick."

Watch Warren's interview with Time here: