Praying with President Obama while filming an episode of Running Wild in the Alaskan wilderness was "one of the most memorable days of my life," TV adventurer Bear Grylls has revealed.

Writing in the Sunday Times magazine, Grylls said: "We discussed the challenges of juggling being a parent with work, our hopes and fears, and at one point we even prayed together.

"That moment was special. It was one of the most memorable days of my life."

According to Grylls, the US President admitted that "he had spent the best part of the past seven years living in a bubble," and used his time in Alaska as an opportunity to "get closer to the natural world".

In September, Grylls tweeted a picture of himself praying with Obama:

Grylls earlier also revealed that around 60 Secret Service agents were on hand during filming, and had tried to stop Obama from taking part in some of the more dangerous activities planned.

"We ended up doing everything and he [Obama] loved it," Grylls said in an interview with Absolute Radio.

"Afterwards, I thought I was going to get a special telling off from the secret service guys, but they all laughed and had a good time."

Grylls is a devout Christian, and told the Radio Times earlier this year that he starts every day in prayer.

"I really, desperately have learnt in my life that I need my faith, and I'm just not strong enough on my own. I try to start every day by kneeling down and saying, 'Lord Jesus, I ain't got it all right, and I'm nervous about today. I will give it my all, but will you help me?'

"It's never more complicated than that. I probably don't go to church enough, but my faith is a quiet, strong backbone in my life, and the glue to our family."

President Obama has also repeatedly affirmed his Christian faith. In 2012, he said his faith had increased during his time in office.

"My faith is a great source of comfort to me. I've said before that my faith has grown as President," he said in an interview with Cathedral Age.

"This office tends to make a person pray more; and as President Lincoln once said, 'I have been driven to my knees many times by the overwhelming conviction that I had no place else to go.'"