At age 35, Spotify co-founder and CEO Daniel Ek is successful by any standard: He's worth a reported $2.9 billion, Spotify had 170 million monthly active users as of May, and the newly public music streaming service reported bringing in nearly $5 billion in revenue last year.
His success is due in part to strict time management rules and a commitment to focus, Ek tells Fast Company. For example, Ek considers the time it would take to catch up with friends better used elsewhere.
"I don't do social calls," Ek says. "For so many people, you're beholden to this social thing, if I don't show up, someone is going to be sad. I'm just pretty ruthless in prioritizing. What I tell my friends is, I like to be invited, but I probably won't come."
While that may seem harsh, Ek explains his behavior is about concentrating his efforts on one thing at a time.
"It's not a personal thing. It doesn't mean that I don't enjoy your company. It just means that I'm focusing on something," he explains.
Ek says he has "daily, weekly, monthly goals," and reviews his progress each night, "over allocating" his time toward those goals, he tells Fast Company.
"People think that creativity is this free spirit that has no boundaries. No, actually the most creative people in the world schedule their creativity," Ek says. "If you're really, really focused, those are the times when the breakthroughs come. I might go for three days and not sleep because I'm focused in that moment."
Ek isn't alone in his obsessive strategy.
Tesla and SpaceX CEO Elon Musk similarly hones in on the tasks he deems important.
"Focus on signal over noise. Don't waste time on stuff that doesn't actually make things better," Musk says.
In fact, Musk is so focused, he has said he sleeps on the factory floor and in April, he revealed didn't even take time to go home and shower when the company's production of Model 3s was behind schedule.
In the early days of his career, Bill Gates was also known for relentless focus on his work at Microsoft. Gates wouldn't stop working to eat lunch most days, according to Mark Penn, Microsoft's former chief strategy officer.
"When I worked with Bill Gates, he would eat right through a meeting, never stopping for lunch. At precisely 12:00 p.m. a hand would come through the door holding a white bag for Mr. Gates," Penn writes in his book "Microtrends Squared. " "In it were two McDonald's Quarter Pounders and a large fries, his daily choice for years."
In fact, "good relationships keep us happier and healthier," according to a 2015 "Ted Talk " by Robert Waldinger, a psychiatrist and professor at Harvard Medical School. In his research, Waldinger found that good health is positively correlated to feeling connected.
"It turns out that people who are more socially connected to family, to friends, to community are happier, they're physically healthier and they live longer than people who are less well connected," he says.
Today, even Bill Gates is taking time to relax more.
"When I was in my 20s and early 30s, my whole life was focused on work," Gates says. "These days, I'm better at balancing the work that I love to do with my foundation and taking time off to spend with family and friends."
Like this story? Subscribe to CNBC Make It on YouTube!