I'm Chris Hemsworth's stunt double. I've been set on fire, smashed through glass, and fallen down dozens of stairs. Here's what my job is like.

• Bobby Holland Hanton is a 36-year old British professional stunt performer for film and TV.
• He's been Chris Hemsworth's stunt double since filming "Thor: The Dark World" in 2012, and has worked in other blockbuster hits like "The Dark Knight Rises," "Inception," "Skyfall," two Harry Potter films, and the latest Mission Impossible, to name a few.
• Hanton grew up as a national-level gymnast, played semi-pro soccer for a few years, and trained in high-diving, kick-boxing, and scuba diving to qualify for the British Stunt Register.
• He works out at least twice each day, follows a high-protein meal plan, and wears heel lifts in his shoes to get a few inches closer to Hemsworth when performing as his stunt double.
• This is his story, as told to freelance writer Mark Williams.

My first-ever stunt on a film set was for "Quantum of Solace," during a night shoot at 2 a.m. in Colón, Panama. I was jumping from one balcony to another with no safety cables, three stories up. I was 23, it was my first film, and it could have been pretty scary if it had gone wrong.

Thankfully, it went great, and I've been doing more wild stunts ever since.

I've smashed through glass, been set on fire, and have done dozens of stair falls and car hits. For "Game of Thrones," we were filming in Seville and I was torched with a real flamethrower, aka Khaleesi's dragons. It was pretty full-on.

I've also doubled for Christian Bale as Batman in "The Dark Knight Rises" in 2012, and did stunts in "Inception," "Avengers: Endgame," "Skyfall," "Wonder Woman," two Harry Potter films, and more.

It takes a lot of work to get onto the British Stunt Register.

I was a national-level gymnast from the age of four to 17. I also played semi-pro soccer for a couple of years, and worked at the Legoland theme park in Windsor, performing in the high-diving show and doing live acrobatics shows around the world through a company called 2MA.

I started training for the British Stunt Register (BSR) when I was 21 and worked on my first film two years later. Being on the register is compulsory here in the UK if you want to work as a stunt performer. They work with Equity, the actor's union.

To get onto the BSR, you have to be considered 'elite' in six different disciplines out of a possible 12, including a martial art. Because of my background, I chose trampolining, gymnastics, and high-diving. For those three, I just took the tests and I passed pretty easily because I had done them all to a high level before.

I also took kick-boxing, scuba diving, and swimming. Kickboxing was something I had no experience in before, so I took classes for two years, eventually getting to brown-belt level. It's turned out to be a very handy skill, because I do a lot of fight scenes in films.

In real life, Chris Hemsworth is a man-mountain who looks like he's been carved out of rock.

At the moment, I'm getting ready to begin shooting for "Thor: Love and Thunder" (the fourth film in the Thor franchise). I double for Chris Hemsworth, who is even bigger in real life, so I've got to start getting big. We're almost the same age, he's 37 and I'm 36, but I have to keep in top shape to keep up.

I first met Chris during the filming of "Snow White and the Huntsman," which I spent a few weeks on, straight after filming "The Dark Knight Rises." We started shooting "Thor: The Dark World" in London in 2012 and I've been his stunt double ever since. We've done 12 films together now.

Stunt doubles don't have to look like the person they are doubling for; the most important thing is your height and body shape. But if there is a resemblance face-wise, that does help, because it means the camera can shoot much closer on you. They can use more footage, which is priceless for them.

I'm not as tall as Chris; he's 6-foot-4 and I'm 6-foot-1. So when I did "Thor: The Dark World" I put 2.5-inch lifts in my costume boots to raise me up a bit. If I'm doing something very dangerous, I take them out, but I usually wear lifts when I stunt double with him.

Before COVID-19, sometimes there would be 60 or 70 stunt performers on set filming a battle sequence.

There's definitely less work about at the moment because of the pandemic (earlier this year, everyone in the industry was out of work for about four months) but it's slowly picking up again. However, there are very strict rules around masks and various precautions you have to take on set.

Before COVID-19, there would often be 60 or 70 stunt performers on set at one time to film big battle scenes. Right now, that's very hard to figure out and do safely. I don't know if production companies have cut certain action scenes from scripts or decided to film them differently; I'd just be guessing. But it's absolutely had a massive impact on the industry and everyone in it. We're all hoping and praying for a return to some kind of normality so everyone can continue what they were doing.

The closure of movie theaters has been devastating, personally and professionally, because this is the industry I work in. People enjoy going to see films on the big screen. It's something that's been a tradition for my wife and I on date night — we love to go out for some sushi before seeing a film.

Stunt performers are athletes, we train at least two or three times a day.

When you start out as a stunt performer, there are standard pay rates if you're with Equity in the UK or the Screen Actors Guild (SAG) in America, where the basic daily rate for a film with a budget of less than $2.5 million is $1,005. It varies for TV and other types of films.

There isn't really a typical retirement age for stunt performers; it depends on the person and their career. If you've made it through without getting many injuries, that plays a big part in how long you can continue, if you train well and look after yourself.

It's very different to the classic stunt performers of the 60s and 70s. Those guys were pioneers but it's moved on, as every industry does, and stunt performers nowadays are athletes.

We train multiple times a day and while I adapt training to the character in hand, as a rule of thumb I do a lot of circuit training and plyometric training because my work is very explosive. We look after our bodies, and I eat strict meals that are high in protein, have a high intake of good fats and good carbs, with one cheat day every Sunday.

One of my closest friends, Glenn Foster, has been Robert Downey Jr's stunt double for 12 years. He's 50 now, but he's in incredible shape and still looks like he's 25. He's coming toward the end of his performing career, and is just starting to move into stunt coordinating, but I'm sure he will continue to perform. It just depends on how you go. You could pick up an injury that you can't shake off, in which case becoming a stunt coordinator is a good way to continue your career

My advice for anyone thinking of becoming a stunt performer is to be absolutely sure it's what you want to do, because it's not for the faint-hearted.

I've done many 16-hour days over the past 13 years. There's big hits, bumps, and bruises, and then you have to get up and do it again the next day even when your body has seized up overnight and is still sore. It's a demanding profession, but I love it, and feel very lucky that I'm getting to do something I'm passionate about.

Mark Williams is a journalist and freelance writer living in London. He has covered business news, travel, sport, and entertainment for a variety of publications. Find more of his work here and say hello on Twitter.