Berkshire Hathaway billionaire Warren Buffett has a lot to be happy about. He is currently the fourth richest person in the world, with a net worth of $90.1 billion.

But Buffett says his financial success isn't the root of his happiness — it's that he enjoys his work and his loved ones.

"I can't buy time, I can't buy love but I can do anything else with money, pretty much. And why do I get up every day and jump out of bed and I'm excited at 88? It's because I love what I do and love the people I do it with," Buffett recently told the Financial Times.

"I've got 25 people out here [at Berkshire]. We go to baseball games together. They try and make my life good, I try and make their life good," Buffett said.

"I'm having a vacation every day. If there was someplace else I wanted to go, I'd go there."

Indeed, Buffett previously told CNBC's "Squawk Box" that relying on money to make you happy doesn't work, saying "even $1 million isn't going to make you happy, it is not going to happen," because then your happiness will disappear when you "look around" and "see people with $2 million," he said.

In fact, Buffett said, even when he was just out of school with only $10,000, he wasn't unhappy because "I was having a lot of fun."

And that remains true today. "This is the pleasure palace here," he told FT about his home at Berkshire Hathaway. "I have more fun here than I think any 88-year-old is having, virtually, in the world."

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