ve been a journalist long enough to know that most actors don’t tend to appreciate being asked how they stay in shape. Most of the time, should you deign to ask such a question, you’ll be met with a barely suppressed eye roll, a non-committal name drop of a Hollywood personal trainer and a swift conversation change back to their directorial ambitions.

Henry Cavill, I am pleased to report, is not one of these actors. In fact, unlike his peers who deem the quest for silver screen-worthy abs a necessary evil of the trade, Cavill’s approach is refreshingly pragmatic. “It’s my job so I’ve just got to do it,” he says. “I’ve got to look a certain way, I’ve got to have a certain amount of health and my body has to be able to do certain things, without breaking, for a long period of time so I’ve got to train.”

It’s an attitude that makes sense for an actor who made his name playing the buffest character in cinema: Superman. And, listening to Cavill talk about his diet and exercise regime, it’s clear this is a man who has done his research – but this wasn’t always so. Pre-Superman, Cavill went up for the role of James Bond between Pierce Brosnan and Daniel Craig and, unbelievably, was told he was too chubby to be the super-spy.

So what helped him turn things around? “I do fasted cardio in the morning,” he explains. It sounds technical but all this really means is working out first thing in the morning, before eating, or 4-6 hours after a meal so your digestive system is no longer processing food. “Then, depending on whether I’m training before or after work, I’ll have breakfast and then go to the gym,” he continues. (Sorry, you don’t get to look like Henry Cavill on one workout a day.)

“It’s normally bodybuilding work because it’s not too neurologically taxing. I found with more explosive workouts, like crossfit, I was so exhausted that by lunchtime I was running out of energy. Body building achieves everything I need to achieve aesthetically, and in terms of the body being able to survive stunt work, without knackering me out.”

Which, on the face of it seems fairly simple. A bit of cardio followed by some body building. Job done. But, of course, there is the little matter of his actual job. “On Witcher season one, I was working 16-17 hour days, sometimes more,” Cavill says. “I was getting up at 2.30am to get to work. I’d go the gym first and then do hair and make-up for two hours and that was the only time I had to learn my lines.” This, gents, is what we call dedication.

Making small changes to his diet, he explains, is what got him through the gruelling routine. Along with his well documented diet of eggs, steak, chicken, potatoes and brown pasta, Cavill says that adding a daily dose of rosemary made all the difference. “I was bone tired, I’d been working six days a week for seven months and was just wishing for it all to end – I mean that in every way possible – but then I started drinking Rosemary Water in the morning and I felt a difference. I felt a lot sharper and had more clarity, lines were just sticking in my head.”

The change, it appears, was so profound that Cavill became a partner of No 1 Rosemary Water – a brand he discovered in the midst of research into starting his own water company. Promising health benefits based on the low cancer and dementia rates and long lives of the people of Acciaroli, Italy – who enjoy a diet naturally high in rosemary – Cavill is such an ardent fan that he’s replaced his entire daily water consumption with Rosemary Water and, well, if works for him…