When you think of Hafþór Júlíus Björnsson, aka Thor Bjornsson, aka the guy who plays "The Mountain" on Game of Thrones, you probably imagine him looking something like this:

 

Giant, savage, wearing a tank top featuring his likeness cuddling his Pomeranian: This is the Thor Bjornsson of your dreams and/or nightmares.

But as many a skinny guy has reminded himself, nobody gets jacked by accident—and Bjornsson himself is happy to confirm that fact. In a series of Instagram posts on Sunday, the Icelandic strongman documented how he'd changed over the four years he'd competed at the annual World's Strongest Man competition.

Here's Bjornsson competing at his first WSM in 2011: 22 years old, 6'9", and 419 lbs (190kg). That was a huge gain from just a year earlier, when Bjornsson was "discovered" by legendary strongman Magnus Ver Magnusson and started competing at around 170kg. And those gains came on top of an improvement of at least 35kg from his days as an Icelandic basketball player, when he'd weighed around 135kg (297 lbs).

 

World's Strongest Man 2011 - My first appearance! 22 years old with no experience. What place did I finish in??

A photo posted by Hafþór Júlíus Björnsson (@thorbjornsson) on

 

Just a year later, in 2012, Bjornsson was about the same height and weight, but he'd advanced in his training dramatically. He placed third, behind Lithuanians Zydrunas Savickas and Vytautas Lalas.

 

World's Strongest Man 2012! 23 years old. Can you name the podium finishers that year??

A photo posted by Hafþór Júlíus Björnsson (@thorbjornsson) on

 

By 2013, Bjornsson was listed at a towering 6'10" (more on that in a moment) and he was noticeably leaner—180kg of muscle, down from 190kg. He finished third again that year, behind Brian Shaw and Savickas.

 

World's Strongest Man 2013! You can see one positive & one negative think about this picture!! #LostWeight #ButStillGettingTaller

A photo posted by Hafþór Júlíus Björnsson (@thorbjornsson) on

 

2014: Although Thor somehow, uh, shrank—we're chalking up that three-centimeter difference to a bad measurement in 2013—and remained the same weight, he improved noticeably on the competition floor, winning three events en route to a second-place finish. And at 25, he was arguably his leanest—and most muscular—of his career:

 

Fast-forward to to 2016, and Bjornsson is up to an astounding 189kg of lean muscle, with two world strongman records to his name: one for the keg toss, and one 1,000-year-old Viking record for carrying a giant (32 feet, 1,433 pounds) log.

So: How'd he do it?

Step 1: Hitting the iron (and tractor-trailers)

As you might expect, Bjornsson focuses heavily on strongman training, which generally challenges athletes to contend with huge weights in awkward positions. (He also breaks some heads on Game of Thrones, but we'll attribute that damage to the HBO special effects department). For example:

 

Training Truck Pull for Worlds Strongest Man 2016! Great training session done in the rain today. #NoExcuses #NeverStopPushingYourself

A video posted by Hafþór Júlíus Björnsson (@thorbjornsson) on

 

He also did a lot of so-called "big rock" exercises familiar to powerlifters—but with some key variations, like wide-grip deadlifts and pause squats:

 

5 reps 3 sets pause squats! One of the exercises I did today! @australianstrengthcoach

A video posted by Hafþór Júlíus Björnsson (@thorbjornsson) on

 

Did shitload of work with wide grip deadlift today. 5 reps 10 sets. #Deadlift #IronAddicts

A video posted by Hafþór Júlíus Björnsson (@thorbjornsson) on

 

Step 2: He ate a ton of really clean food, all damn day.

Back in May, Bjornsson documented the epic diet plan he'd been following throughout the most intense part of his training cycle ahead of his strongman competitions. With some educated guesses (one Thor-sized handful is probably two normal-man-sized handfuls), we added up everything he ate and found that he probably consumed a total of 5.9kg of food a day, spread out through nine meals.

His go-to foods: chicken, salmon, and beef, plus almonds, eggs, potatoes, greens, and a few Rice Krispies thrown in for good measure. He specifically points out that the average guy shouldn't try it, but it does give you an idea of the sheer quantity strongman competitors need to maintain their weights. (Here's Bjornsson's full diet plan).

Interested in training like Bjornsson? Here are three simple ways to add strongman training into your workout, and five things to expect when you start strongman training.