Bill Gates' mastery of this productivity technique fueled his massive success

It was February 1975 and Bill Gates, a Harvard sophomore who looked 15 years old at best, typed line after line of code that would become the software behind Microsoft, which would launch two months later.

Gates, his business partner Paul Allen, and a Harvard math student named Monte Davidoff spent two weeks in the school's Aiken lab. Gates was particularly relentless, forgoing studying for exams to build the software.

As author Walter Isaacson writes in a 2013 issue of the Harvard Gazette:

In the wee hours of the morning, Gates would sometimes fall asleep at the terminal. "He'd be in the middle of a line of code when he'd gradually tilt forward until his nose touched the keyboard," Allen said. "After dozing an hour or two, he'd open his eyes, squint at the screen, blink twice, and resume precisely where he'd left off - a prodigious feat of concentration."

It's a perfect example of "deep work," Georgetown professor and author Cal Newport says in his new book of the same name, and it's the reason why Gates had such a remarkable rise to success while still in his early 20s.

Newport defines deep work as "professional activities performed in a state of distraction-free concentration that push your cognitive capabilities to their limit, [which then] create new value, improve your skill, and are hard to duplicate."

Newport also quotes Isaacson's 2014 book "The Innovators" to bolster his point. "The one trait that differentiated [Gates from Allen] was focus," Isaacson writes. "Allen's mind would flit between many ideas and passions, but Gates was a serial obsessor."

In a 2014 Reddit Ask Me Anything interview, Gates writes that in his older years as a philanthropist, he has channeled his obsessive nature primarily into the Bill & Melinda Gates Foundation and tempered it with a more reasonable schedule, but that "20 years ago I would stay in the office for days at a time and not think twice about it."

Newport argues that it's not as simple as equating hard work with success. Rather it's about understanding how - more than ever in the age of constant internet connectivity - perpetual distractions threaten to limit our potential and minimize the impact of our work.

You don't need to take it to Gates' level and regularly work through the night at the office. A dedication to deep work requires setting aside stretches of time each week (of say an hour or two) when you work with urgency and your concentration is not disrupted by anything, not even a brief moment of daydreaming or getting up for a cup of coffee.

It's about being constantly aware of what work is considered "shallow" and what is "deep," and ensuring that shallow work doesn't overtake your schedule.

"A commitment to deep work is not a moral stance and it's not a philosophical statement - it is instead a pragmatic recognition that the ability to concentrate is a skill that gets valuable things done," Newport writes. "Deep work is important, in other words, not because distraction is evil, but because it enabled Bill Gates to start a billion-dollar industry in less than a semester."