"It's 21 days of prayer and fasting," he announced in an Instagram video.

Pratt said he's hoping to lose weight and connect to his faith during the fast.

He also made a joke in the post from his Instagram story saying the fast coincides with the Lego Movie 2 junkets ... so he might end up hallucinating from exhaustion ... so "stay tuned!"

The Daniel fast is specifically laid out in the Bible in the book of Daniel. It includes fasting from foods like meat and sweets and replacing them with vegetables, fruits, whole grains, nuts, seeds, legumes or beans, and water.

Many Christians do it for their health and as a way to draw closer to God, often at the beginning of a new year.

Pratt has been bold about living his Christian faith in public over the past few years. At the Teen Choice Awards in August 2018, he told his fans, "I love God and you should too."

And he opens up about his real-life struggles too. In one Instagram post last year about a nightmare he had, Pratt says: "That's the anxiety I get sometimes. That I'm not working hard enough. That I'm not prepared. That I haven't put in the work. Not today devil! Today we put in the work. If a nightmare hits you. Hit back. And know that when you follow God you are never alone."

Shortly after that he quoted a Bible verse in another post: "Get it in. Every day. Stoked to work out with good people including UFC veteran @uriahhall today. Blessed to be healthy and hungry. "Like Iron sharpens iron, so too one man sharpens another" Proverbs 27:17. Subscribe for free to Breaking Christian News here

To receive daily emails from Breaking Christian News to your inbox CLICK HERE

Skeptical Doctor Shocked After Blind Son's Miracle Healing, Husband's Near-Death Experience

Louisiana Pastor Sues Library After Being Fired over Preferred Pronouns

Trans Athletes Drop Challenge to New Hampshire Women's Sports Law

30,000 'Trojan Horses': Europe and Britain Face Muslim Domination and Escalating Threat of Civil War

Consumer Prices See Steepest Monthly DECLINE in More Than Six Years in June

Documents Reveal: Democrat Special Counsel Jack Smith Spied on, Lied to Congress

The Deal Ensuring Conservatives' Border Security and SAVE America Act

Speaker Mike Johnson Issues Serious Warning About Communism and the DSA: 'This is Not a Game' (VIDEO)

Revival Grips Brazil's Amazon: 'God Is Everything for Me'

More Arson? Investigators Sift Through Ashes at Landmark 173-Year-Old Church Searching for Clues

Shocking Survey: More than Two-Thirds of Gen-Z Don't Know What America 250 Commemorates (Video)

US House to Vote on Bill Making Daylight Savings Time Permanent

What to Know About Darline Nordone, Lindsey Graham's Sister Appointed to Fill His Seat

Amid Renewed War against Iran's Islamic Regime, the Country's People Once Again Take to the Streets in Anti-government Protests

US Pounds Iranian Targets After Blockade Reimposed; Trump Scraps 20% Fee for Trade Deals

'Abundant Life': Study Finds Bible-Reading Is Better Self-Care Than Exercise

A New Low: Doctors Are Now Making the Case for Death by Organ Donation

Trump Administration Launches Anti-Predator Initiative for Schools K-12

US Targeting Islamic Republic Army Bases, Strikes IRGC Nuclear Town; People of Iran React to Sen. Graham's Death

Cause of Death Revealed for Lindsey Graham, Pro-Life Champion and Strong Defender of Israel