Here's how billionaire Mark Zuckerberg defines happiness

Forget the vacations and private getaways - for Facebook founder and CEO Mark Zuckerberg, happiness is all about helping others with the ones he loves.

During a Q&A on Facebook last month, Zuckerberg answered a ton of questions and wrote a great deal about how people play a huge role in his life and work:

To me, happiness is doing something meaningful that helps people and that I believe in with people I love.

I think lots of people confuse happiness with fun. I don't believe it is possible to have fun every day. But I do believe it is possible to do something meaningful that helps people every day.

As I've grown up, I've gained more appreciation for my close relationships - my wife, my partners at work, my close friends. Nobody builds something by themselves. Long term relationships are very important.

Considering Zuckerberg was a psychology major before he dropped out of Harvard, his marriage to college sweetheart Priscilla Chan, and his history of forgoing fancy cars, clothes, and a salary, his answer isn't all too surprising.

But it's a refreshing change of pace to hear such a down-to-earth response from a man running one of the most successful tech companies in the world who's currently worth close to $40 billion, according to Forbes.