Yorkshire boss criticised for urging people to work seven days-a-week 'or they won't achieve much'

Christian Nellemann, founder of Sheffield utilities firm XLN, said that as well as putting the hours in ‘you have to work with intensity’ and ‘it is no good having breaks all the time’.

In a Linkedin post he asked: “Are you guilty of not working hard enough?”

He wrote: “If you are not prepared to work 12–18 hours a day, six or seven days a week, then you are not going to achieve much or become a big success. It is that simple. And you have to work with intensity. It is no good having breaks all the time.

“The magic equation to remember is: Hours × Intensity × Ability = Results

“You have got to put the hours in, but simply sitting at your desk isn’t going to achieve anything; you need to work with intensity too. This is hard to do in the beginning, but if you stick at it, you will end up putting four times as much effort in over a lifetime, meaning you will be eight times further along the road.

“Do you put enough effort in to achieve real success?”

XLN employs scores of people in One North Bank on the Wicker. The firm sells bundles of utilities for small businesses.

The post attracted hundreds of responses. Most were critical, accusing Mr Nellemann of being irresponsible, misleading and dangerous - and some asked if it was a joke.

Kev Anderson said: “Utter nonsense and actually a very irresponsible message to share. I’m old enough and wise enough to see this for what it is… and what it is, is the worst possible advice you could share.

“My biggest concern is that younger people or less experienced entrepreneurs read this and actually believe it.

“The lifestyle you promote here is unhealthy, unsustainable and a slippery slope to burnout and a mental health breakdown.”

Rebecca Robinson said: “Is this a joke?”

Tim Turner added: “This mentality will kill people and ruin lives. I’m trying to imagine a life so empty that working yourself to death in pursuit of someone else’s definition of success.”

Matt Spivey said simply: “Or you could have a life.”