Christmas came early for John Krasinski fans. The actor, best known for his role as the lovable Jim Halpert on the hit TV series "The Office," showed off his hot, new muscular physique on the January/February cover of Men's Health and dished about how he got ripped in just four months for his role as a Navy SEAL in the upcoming film "13 Hours: The Secret Soldiers of Benghazi."

The 36-year-old star showed off the results of his fitness and diet routine, which allowed him to build muscle and burn fat. He prepared for the role by working with trainer Jason Walsh, according to Men's Health.

"Getting stronger every day is thrilling," said Krasinski. "I gotta be honest: It was brutal at times. We did tons of metabolic work, dragging sleds and all this stuff I've seen NFL players do."

Krasinski also dished to late night host Jimmy Kimmel about his strict diet and workout schedule in which he reduced his total body fat percentage from 25 to 9 percent.

"Basically eating salads and chicken and water. And working out all the time, we did two-a-day workouts," Krasinski told Kimmel.

He got jacked for his role as U.S. Navy SEAL Jack in the upcoming Michael Bay film "13 Hours: The Secret Soldiers of Benghazi," which is based on a 2014 book that tells the true story of a group of soldiers who responded to the 2012 Benghazi attack, according to IMDB.

See the photos and watch a behind-the-scenes clip from Krasinski's photo shoot below.