Boris Johnson has hired personal trainer Harry Jameson to lose weight, after acknowledging he was "too fat" when he caught coronavirus.
The prime minister was admitted to hospital with the virus in April but says he has since "been steadily building up my fitness".
Mr Jameson says his training "considers the mind as much as the body".
The coach has also helped Love Island host Laura Whitmore train and has a regular slot on her BBC radio show.
Mr Johnson's time in intensive care is thought to have prompted a change in his views on tackling obesity.
He has previously criticised levies on foods high in salt, fat and sugar - and characterised his stance as "libertarian".
In July he said that while he was not normally one for "nannying or bossying", the country did need to lose weight to protect from a second spike.
"Obesity is one of the real co-morbidity factors. Losing weight, frankly, is one of the ways you can reduce your own risk from coronavirus," he said.
As part of a drive to tackle the problem, the government said it would ban TV junk food adverts before 21:00.
On a personal level, Mr Johnson has said he had "wanted to lose weight for ages" adding that he "struggled" to keep fat off.
He said that since leaving hospital he had lost "at least a stone" by going for a run with the dog.
Speaking to the BBC's Fit & Fearless podcast, the prime minister's new trainer, Mr Jameson, said he seeks to help his clients "in ways beyond pumping weights in the gym".
He says his approach has "always been based on a foundation of mind and body together and ultimately happiness".
He studied sports science and psychology at Liverpool Hope University and has worked as a personal trainer for 15 years.
Like the prime minister, Mr Jameson also appears to be a fan of the classics having quoted the Roman philosopher Seneca ("as long as you live, keep learning how to live") in a speech to the Balance Festival in 2018.