Ballmer choking up as he says good bye to Microsoft employees. Microsoft / The Verge Steve Ballmer has given his exit interview to The Wall Street Journal.

In it, he gives his fullest explanation for why he's stepping down as CEO of Microsoft.

It sounds like Ballmer decided it was time to leave after getting a certain amount of nudging from his board members.

In January, Ballmer was laying out his plan to combat the rise of the iPhone and Android to his board members in a conference call. He was cut off by John Thompson, lead director.

"Hey, dude, let's get on with it... We're in suspended animation," Thompson said.

That conversation set in motion Ballmer's decision to step down. He realized he couldn't move fast enough to make the board happy.

Thompson says the board "didn't push Steve to step down, but we were pushing him damn hard to go faster."

Ballmer was trying to go faster. He enacted a reorganization of the company. He tried to make the company more collaborative, but his senior team was thrown off by the "New Steve," says the WSJ.

By May, Ballmer started to doubt that he could change the company as quickly as the board wanted.

"No matter how fast I want to change, there will be some hesitation from all constituents—employees, directors, investors, partners, vendors, customers, you name it—to believe I'm serious about it, maybe even myself," said Ballmer.

So, he decided to retire with the hope that the next CEO would be able to come in and shake up the company and move more quickly.

Ballmer teared up as he explained his decision, saying, "Maybe I'm an emblem of an old era, and I have to move on ... As much as I love everything about what I'm doing, the best way for Microsoft to enter a new era is a new leader who will accelerate change."

Read the whole thing at The WSJ, there's more »