Ofsted's controversial chief inspector today launched a stinging attack on heads and teachers who make excuses and complain about their jobs, saying they do not know what stress is.
England does not need school leaders whose first instinct is to blame others for failure, but those that are willing to tackle under-performance, Sir Michael Wilshaw warned.
Heads have more power, pay and freedom than ever before and should recognise the "privileged" position they are in, he said.
Wilshaw also vowed to press ahead with his proposals to raise school standards in the face of widespread criticism from headteachers.
He told a conference at Brighton College this morning that in the past, headteachers who were not prepared to tackle poor teaching were not challenged.
"We need to learn from this and challenge those who have power invested in them to make the difference, but too often make excuses for poor performance - it's just too hard, the children are too difficult, the families are too unsupportive, this job is far too stressful," Wilshaw said.
"Let me tell you what stress is.
"Stress is what my father felt, who struggled to find a job in the 1950s and 1960s and who often had to work long hours in three different jobs and at weekends to support a growing family.
"Stress is, I'm sure, what many of the million and a half unemployed young people today feel - unable to get a job because they've had a poor experience of school and lack the necessary skills and qualifications to find employment.
"Stress is what I was under when I started as a head in 1985, in the context of widespread industrial action - teachers walking out of class at a moment's notice - doing lunch duty on my own every day for three years because of colleagues who worked to rule - covering five classes in the sports hall when there was no-one to teach them.
"Stress was, in the days before local management of schools, writing letters in triplicate to the local authority asking for a brick wall to be built in the playground or for a bit of extra money to keep an excellent maths teacher - and not receiving a reply for weeks.
"I still bear the scars of those days."
Wilshaw said that times have changed, and that heads are now in charge, with better pay and more independence, power and resources than before.
"We need heads who know what a privileged position they are in now and who can use their new-found independence well - people who roll up their sleeves and get on with improving their schools, even in the most difficult circumstances.
"What we don't need are leaders in our schools whose first recourse is to blame someone else - whether it's Ofsted, the local education authority, the government or a whole host of other people."
Wilshaw told the conference that the bar on school standards must be raised.
"We must hold our nerve," he said.
"I am determined to do so as chief inspector, and not panic at the first whiff of grapeshot, some of which has whistled past my ears over the last few days."
The union passed an emergency motion which said they were "saddened and dismayed" by his approach.
The move represented a further deterioration of relations between the union and Ofsted, and came just days after the NAHT raised concerns over the variable quality of inspections and the watchdog's planned changes to the inspection system.
Proposing the motion, Mike Curtis, an Oxfordshire headteacher, had told the NAHT's conference: "Fear reigns and confidence wanes as Ofsted waves its stick!"
It is time to stand up to "bully-boy tactics", he added.
Education Secretary Michael Gove backed the Ofsted chief in his speech to Brighton College today, telling delegates: "There's been some criticism recently of the new inspections framework and the new chief inspector.
"I've listened to that criticism - I've considered carefully the arguments made - and I have to say on reflection - it's misdirected at best, mischievous at worst.
"Sir Michael Wilshaw is a visionary school leader who has spent his career in the state sector and has achieved amazing results for children from the poorest homes - when his critics achieve results like him, then I'll believe their arguments carry the same weight as his experience.
"He is determined to improve inspection, drive up standards, encourage great teaching and celebrate good leadership - he deserves the backing of everyone who wants children to succeed - and I shall do everything to ensure that whatever he wants - he gets."
Brian Lightman, general secretary of the Association of School and College Leaders, said: "Committed, hard pressed school leaders who have been working tirelessly to raise standards despite a climate of public denigration, job vulnerability and spending cuts know exactly what stress is.
"Asking the chief inspector to stop denigrating the profession and to recognise the challenges school leaders face, especially in schools in disadvantaged areas, is not, in my book, blaming others."
Dr Mary Bousted, general secretary of the Association of Teachers and Lecturers (ATL), said: "Please will Ofsted concentrate on helping schools improve and stop criticising teachers and heads.
"It is really not helpful for Sir Michael Wilshaw to rubbish the amount of stress teachers are under.
"And Ofsted is part of the problem with its continual changing of the inspections goalposts and ridiculous demands for lessons to be exciting at all times."
On-duty police officers applaud as thousands of off-duty police officers march pass Downing Street in London as they take part in a protest march against proposed changes to their pay and conditions, in London, Thursday, May 10, 2012. Up to 16,000 police officers, who are banned from striking under law, donned black caps representing each officer expected to be lost under the Government's budget cuts as they took to the streets of London Thursday. (Photo credit: AP Photo/Sang Tan)
A protester holds up a placard in front of Downing Street in London as thousands of off-duty police officers march past in a protest against cuts in the police service, Thursday, May 10, 2012. (Photo credit: AP Photo/Sang Tan)
Police officers and public sector workers march through central London during a day of protest across the country on May 10, 2012 in London, England. A reported 400,000 public sector workers across the country are taking part in a twenty four hour strike in dispute over government changes to pensions. (Photo credit: Dan Kitwood/Getty Images)
Andy Coulson, former editor of the News of The World and former director of communications for the Conservative Party, arrives at The Royal Courts of Justice to give evidence to the Leveson Inquiry on May 10, 2012 in London, England. This phase of the inquiry into the culture, practice and ethics of the press in the United Kingdom is looking at the owners of various media groups. The inquiry, which may take a year or more to complete, comes in the wake of the phone hacking scandal that saw the closure of The News of The World newspaper in 2011. (Photo credit: Christopher Furlong/Getty Images)
Syrians inspect a crate at the site of twin blasts in Damascus on May 10, 2012. Two powerful blasts in quick succession rocked the Syrian capital at morning rush hour, killing and wounding dozens of people, state television said, blaming the attacks on 'terrorists.' (Photo credit: LOUAI BESHARA/AFP/GettyImages)
Syrians inspect damages at the site of twin blasts in Damascus on May 10, 2012. Two powerful blasts in quick succession rocked the Syrian capital at morning rush hour, killing and wounding dozens of people, state television said, blaming the attacks on 'terrorists.' (Photo credit: LOUAI BESHARA/AFP/GettyImages)
A high priestess, holds a torch with the Olympic flame during the lighting of the flame ceremony on Thursday, May 10, 2012, in Ancient Olympia, Greece. The flame will be carried from the birthplace of the Ancient Olympics to London, where the 2012 Summer Games will take place from July 27-Aug. 12. (Photo credit: AP Photo/Petros Giannakouri
A relative weeps as she waits for the news on the missing Russian airplane at Halim Perdanakusuma airport in Jakarta, Indonesia, Thursday, May 10, 2012. The wreckage of the Sukhoi Superjet-100 passenger plane that went missing during a demonstration flight Wednesday near Jakarta was spotted Thursday in a mountainous area of West Java. (Photo credit: AP Photo/Tatan Syuflana)
An Elderly woman participates in a protest in New Delhi, India, Thursday, May 10, 2012. Hundreds of elderly from the country are protesting near the Indian parliament for the last three days demanding universal old age pension for those above 60 years of age. (Photo credit: AP Photo/ Manish Swarup)
Protestors shout slogans during a general strike to pressure lawmakers drafting the Himalayan nation's new constitution not to divide the country into states based on ethnic population which could fuel racial conflicts later, in Katmandu, Nepal, Thursday, May 10, 2012. Police says they have detained more than 50 protesters who were enforcing a general strike called to pressure lawmakers drafting the Himalayan nation's constitution. (Photo credit: AP Photo/Niranjan Shrestha)
Kashmiri government employees shout slogans as Indian police use colored water from a water cannon to disperse them in Srinagar, India, Wednesday, May 9, 2012. The employees demanded payment of arrears in salaries and raising of retirement age, among other demands. (Photo credit: AP Photo/Mukhtar Khan)
Fancy rat Vaice wears fan gear of German Bundesliga soccer club Borussia Dortmund during a photo call for the trade fair Dog & Pet (Hund & Heimtier) in Dortmund, Germany, 09 May 2012. More than 8500 dogs from 35 countries representing 267 breeds are expected at Westfalenhalle for the VDH European Champion Exhibition from 11 till 13 May 2012. Cats, fish, reptiles and rats, et al will also be on view. (Photo credit: BERND THISSEN)
Wounded Syrian soldiers react following a roadside bomb attack which targeted their convoy as they escorted UN peace observers, including the Norwegian general who heads the mission, in the restive southern Syrian city of Daraa on May 9, 2012. Six soldiers were wounded when the explosive device, which appeared to have been planted underground, detonated as the convoy of four vehicles was about to enter Daraa, cradle of a 14-month uprising against President Bashar al-Assad's regime. (Photo credit: LOUAI BESHARA/AFP/GettyImages)
Tulips to pick yourself shine in various red tones near Schondorf, Germany, 09 May 2012. (Photo credit: KARL-JOSEFÂ HILDENBRAND)
Dancer TsaiÂ Ming-yuan and Ko Wan-chen dance during a press rehearsal for the European premiere of the piece Water on the Wall by the Cloud Gate Dance Theater of Taiwan in Wolfsburg, Germany, 09 May 2012. The Moviementos dance festival runs until 20 May with dance, readings and concerts. (Photo credit: JOCHENÂ LUEBKE)
A Kenyan Tribesman performs in the rain during the dress rehearsal of the Diamond Jubilee Pageant which runs from Thursday 10th May to Sunday May 13th in the grounds of Windsor Castle, Berks. (Photo credit: Steve Parsons/PA Wire)
The Carousel of the Carabinieri perform in the rain during the dress rehearsal of the Diamond Jubilee Pageant which runs from Thursday 10th May to Sunday May 13th in the grounds of Windsor Castle, Berks. (Photo credit: Steve Parsons/PA Wire)