Kit Harington, Game of Thrones star, put on two stone of muscle to play Milo in Pompeii.
His role as Jon Snow also requires high fitness levels, as the character is a fighter in many battles, and rides from horses and dragons.
Wearing heaving armour requires a certain amount of strength, as does waving around a sword.
Kit spoke with Men’s Health about maintaining his fitness level, and put a lot of it down to staying so active while shooting for Game of Thrones.
He said: “The physical stuff is very much a part of who Jon Snow is and over the four years I’ve got into rock climbing, ice climbing, sword fighting and horse riding.”
The British actor also revealed what he eats to stay in shape.
He revealed her ate a whopping 5000kcal for five weeks to build muscle.
She said: “I was eating all the time: loads of good carbs, like brown rice and sweet potatoes. And lots of chicken.”
His trainer also told the magazine: “We were doing a lot of full-body movements, rather than the typical isolation exercises.
“Lots of cable routines that would allow his body a fuller range of movement, because he would have to take that sword around the head.”
Another Game of Thrones star Nikolaj Coster-Waldau also has an impressive physique.
The actor, who plays Jaime Lannister, does bodyweight exercises to help him stay in shape and tried to bulk up in 2017.
Speaking to Men’s Health at the time, he said his exercise plan included pull-ups, push-ups and the Navy SEAL burpee, which includes more push-ups than a regular burpee.
“We did a ton of basic bodyweight stuff,” he revealed.
“But then on top of that, in the gym I would try to bulk up so I’d do a lot of deadlifting, a lot of squatting, a lot of those things.”
A man on Reddit revealed the weight loss diet plan than helped him lose 3.2 stone and belly fat, revealing six pack abs.
The 25-year-old man detailed exactly how he lost the weight.
Initially the dieter weighed 15 stone, or 210lbs. Now, he weighs a much lighter 11.7 stone.
So what weight loss rules did he follow? The young man wrote that he went though “five months of 1500 calories a day, HIIT sprints, gruelling workouts, and not eating after 7 pm.”