After thirty long years, Microsoft CEO Steve Ballmer finally stepped down this year, signalling the end of an era at the tech titan. For the first time since his announcement, Ballmer opened up to the Wall Street Journal about his departure. 

Last year Ballmer, 57, was facing intense pressure from Microsoft executives to turn around the company, and to do it quickly. Ballmer had been the company's CEO for over thirty years, guiding them from his Harvard dorm room with classmate Bill Gates to record profits, but his time was starting to wind down. The company failed to capitalize on the emerging mobile or social markets. "Maybe I'm an emblem of an old era, and I have to move on," Ballmer tells the Wall Street Journal now. "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."

In October, he told the Microsoft board his plan was to stay with Microsoft for another four years. He wanted to wait until his youngest son graduated high school before retiring. Ballmer even started holding "cloak-and-dagger" meetings to find his eventual successor. After meeting with a friend, longtime Ford executive Alan Mulaly, Ballmer vowed to change his management strategy. He usually ordered his lieutenants to hand in detailed reports, and encouraged divisional competition. His new initiative was meant to foster cooperation and simplicity. His lieutenants weren't sure how to handle the "New Steve." Ballmer's fellow executives wanted Microsoft turned around quicker than Ballmer's four-year plan, and they weren't hesitating to let their dissatisfaction known. 

That's when Ballmer realized it was his time to leave

Mr. Ballmer says he started to realize he had trained managers to see the trees, not the forest, and that many weren't going to take his new mandates to heart.

In May, he began wondering whether he could meet the pace the board demanded. "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," he says.

His personal turning point came on a London street. Winding down from a run one morning during a May trip, he had a few minutes to stroll, some rare spare time for recent months. For the first time, he began thinking Microsoft might change faster without him.

"At the end of the day, we need to break a pattern," he says. "Face it: I'm a pattern."

Shortly thereafter, Ballmer drafted his letters of resignation and informed the appropriate people that he would, in fact, leave the company so new blood can take over. As it turns out, Mulaly is one of the top candidates to replace him. 

Since announcing his plans to step down in August, Ballmer has done well for himself. The now-former Microsoft CEO made $1.7 billion since his departure from the computer company, so there's no reason to cry for him. (He was already a billionaire, but still: leaving your baby is always hard.) It was an amicable departure, too, with a proper send off at his last employee meeting that included a special mix-tape. Break-ups are always easier with mix-tapes.