Facebook founder and CEO Mark Zuckerberg told all in a surprise Q&A session on Friday. On a rare occasion, he bravely answered questions about topics ranging from his technology to net neutrality, his working habits, and Internet.org.

One of the most interesting revelations was that he admitted to spending only 50 to 60 hours in office work and meetings.

"That depends on what you count as work. I spend most of my time thinking about how to connect the world and serve our community better, but a lot of that time isn't in our office or meeting with people or doing what you'd call real work. I take a lot of time just to read and think about things by myself. If you count the time I'm in the office, it's probably no more than 50-60 hours a week. But if you count all the time I'm focused on our mission, that's basically my whole life," Zuckerberg answered.

But don't judge Zuckerberg if he said "only" up to 60 hours per week, because he is actually working longer than the average American. A Gallup survey released last year showed that full-time workers reported an average of 47 work hours per week. The Facebook CEO is one of the 18 percent full-time employees who spend at least 60 hours per week working.

It's also a mistake to think that working long hours per week can make you successful like him. While occasional overtime work can make you earn more cash or look good to your boss, over-extending yourself can affect your health and quality of life. According to a study conducted by the Aragon Institute of Health Sciences, people who work more than 40 hours a week are six times more likely to experience burnout compared to those who work less than 35 hours per week.

So what's Zuckerberg's advice for success? "Don't give up." Yes, it's as simple as that.