The BBC's weekly The Boss series profiles a different business leader from around the world. This week we speak to Bill McDermott, the chief executive of German business software group SAP.
When Bill McDermott lost an eye in a freak accident three years ago, he returned to work as soon as he could.
The American boss of Germany's SAP spent almost 10 hours in an operating theatre in 2015, after he fell down the stairs at his brother's home while holding a glass of water, which shattered into his face and neck.
Recovering after the operation, which cost him his left eye, his first thoughts were to telephone SAP to assure colleagues that he was fine. Two months later Mr McDermott was back at work.
"It never, in my wildest imagination, entered my mind that I wasn't coming back to work," he says, speaking at SAP's North American headquarters in New York.
The 57-year-old's swift return to the office is indicative of the drive and work ethic that has helped him rise from owning a delicatessen aged just 16, to becoming the highest-paid boss of a German public company - last year he was awarded €21.8m ($24.8m; £19.5m) in pay and benefits.
Raised in a working-class household in Long Island just outside New York City, Mr McDermott got his first job at the age of 11 delivering newspapers, so that he could help with the family finances.
Stints then followed at an Italian restaurant, a petrol station and a supermarket, before he started working at a local deli.
"My little jobs, whether I was delivering newspapers or working at a supermarket, I loved them all. I loved work because I wanted to be somebody," he recalls.
When the owner of the deli wanted out, Mr McDermott, aged 16, offered to buy the business.
He didn't have the money, but in an early display of his knack for deal-making, he convinced the owner to lend him some of the funds.
He made such a success of the shop that he was able to fund himself through college, repay the loan, and buy his parents a holiday home.
He entered the corporate world in 1983 when he got an entry-level sales position at then-photocopying giant Xerox.
He wasn't shy about his ambition. In his 2014 memoir he recalls telling the Xerox hiring manager, "Sir, one day I would hope to become the CEO."
Mr McDermott quickly rose through the ranks at Xerox, but ultimately grew frustrated as the firm struggled to adapt to the changes wrought by advances in computers and email.
In 2000, after 17 years, he left for a job at business research and consultancy group Gartner, then worked at software company Siebel Systems.
In 2002, SAP brought him on to lead and reinvigorate its North American sales.
Eight years later he was named co-chief executive of the whole business. "That was the call I was waiting for all my life," he says. "I finally felt, at least for a few days, that I had arrived."
In 2014 Mr McDermott took over as SAP's sole chief executive, the first American to head the company, and the only American leading a business listed on the Dax, the main German share index.
The promotion prompted fears of layoffs at the business, and worries that SAP faced an unwanted "Americanisation", according to news reports at the time.
Former colleagues at Xerox also questioned whether a colourful American could successfully lead a staid German business.
Anne Mulcahy, a previous chief executive of Xerox, told CNBC in July last year: "Bill is kind of an out-there kind of guy. I mean, we all wanted him to be wildly successful [at SAP]. But I gotta tell you, we were all saying, 'Could this possibly work?'"
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Mr McDermott says he "did not get caught up" in any of the doubts about his suitability to lead SAP.
Instead, he led a charge into new areas, aiming to keep the firm on top of the the massive changes occurring in the software and data industries.
Under his leadership, the 46-year-old company has made a series of acquisitions, expanding its product range, and moving into cloud computing.
Revenues have soared, rising to nearly €23.5bn ($26.7bn; £21bn) last year, almost 90% higher than in 2010 when Mr McDermott initially became co-chief executive.
Over the same period SAP's profits have more than doubled, and the share price has climbed from about €38 to €94, making it the most valuable company on the Dax.
Mr McDermott says that whether at SAP or Xerox, he has always been guided by the lessons he learned behind the deli counter as a teenager.
"In this business or in that little old delicatessen, it was always about understanding that customer, not just what they need today, but what they're going to need next," he says.
Paul Saunders, a research director at Gartner, says that at times SAP's rhetoric about serving customers has failed to match reality, pointing to a recent controversy about how the firm disclosed certain fees to customers.
"They've owned up to those missteps, but that taste in people's mouths just doesn't go away very quickly," says Mr Saunders.
However, he adds that Mr McDermott's charisma should be an asset to SAP as the firm tries to evolve from being "just a bunch of really smart, technical German engineering people, to a company that understands what businesses need".
Mr McDermott's current contract runs until 2021. Whatever happens in the future, he says he has no intention of slowing down.
"I'm a worker and I love work, and I will always work," he says. "I think about retirement as a punishment."