"I was working at the University of Surrey and alongside running a sports injuries clinic and training athletes I also taught climbing and skiing," he tells me over the phone from Abu Dhabi, just after the last GP.
"A guy came in for a climbing lesson one day who worked for McLaren. He was looking for someone to do all the sports therapy work with the McLaren F1 drivers and asked if I'd be interested and it went from there.
"In all honesty I had no real interest at the time in F1, never watched it and here I am 18 years later!"
Arnall begin working with Mika Hakkinen before concentrating on Raikkonen, moving with the Finn across teams and disciplines including rally and Nascar before returning to F1 and Ferrari.
After 14 years working together, Arnall and Raikkonen know how to work with each other and also give each other enough space.
"For me he's great to work with ... what you see is what you get ... zero bullshit! Straight, honest to the core and a great sense of humour (that very few people really get to see)."
As Raikkonen's career has changed, so too have the demands on a driver over the years.
"Formula 1, in all honesty has become less physical," says the 43-year-old.
"At the start of a race now the cars are full of fuel so are around three to five seconds slower than in qualifying. We also have less downforce so cornering speeds are lower. There is more emphasis now on making the driver as light as possible.
"Muscle weighs four times as much as fat, because of this we focus more on cardio work, endurance, HIIT (high intensity interval work) functional and corrective work and less on pure strength work."
Primary goal is to keep the driver in one piece, he says.
A driver's diet has also slowly adapted. "Thankfully Kimi eats a healthy diet. We don't use a stupid number of supplements as I prefer to get good nutrition through the food," Arnall says.
But an important aspect of keeping Raikkonen track-ready is hydration.
"Fascia (connective tissue in the body) reacts very well to being fully hydrated and causes lots of problems when it's not. So I focus on making sure Kimi is well hydrated at all times," says Arnall.
"This is obviously more challenging in hotter or more humid environments but the advantage of working with someone that long is you know how their body works."
On race days, as the Ferrari sits in the garage, waiting for Raikkonen to take to the track, Arnall will be standing alongside.
Just what is he doing at that point?
"I have the drinks bottle for the driver, cloth and cleaner for the visor, face towels, pockets full of everything I think I might need for the driver while he's in the car."
Outside of the garage the job Arnall does now has expanded from the early days of "just" being the masseur.
"At the track it's more making sure Kimi only has to focus on driving the car. "I have a massage couch that follows me around the world as well as a full medical kit," he says.
"I look after all the team kit, helmets, overalls, gloves etc. Kimi prefers to keep using gloves and boots until they fall apart so I carry these with me in my carry-on luggage everywhere so they don't go missing, get given away etc."
Arnall also works with the marketing team to make sure Raikkonen is "in the right place at the right time".
"I also help make arrangements for friends and family who come to the races in terms of passes, pick-ups etc so Kimi doesn't have to worry about it.
"I also book the majority of Kimi's travel to and from races and work with the hotels in advance to make sure we have everything we need when we arrive."
So, there must be downsides to the job?
"When the car is pants it can make the year drag a bit. But I can honestly say that the vast majority of my life in F1 has been really positive, even when the car isn't as competitive as you would want!
"So I'm lucky to do something I really enjoy! Life is what you make of it, can't see the point of being negative ... If you don't like what you do you should try and change it."
Like all people in F1, life is a constant travelogue, non-stop for more than eight months of the year, so where is home?
"It's 38,000 feet."
That nomadic, often singular lifestyle, can crush many a relationship.
"I have a girlfriend. She runs her own hotel consultancy company and that allows her to travel to quite a few of the races with me which keeps our relationship alive. F1 is a killer in that department.
"We've worked hard to create a life situation that allows us to still manage to spend a lot of time together."
The final word goes to Arnall after I asked him if there was anything he would like to comment on. "To quote Kimi Raikkonen, 'No'."
- Bob McMurray, Driven
