Former Microsoft CEO Steve Ballmer turns 68 years old today, and the sixth richest person in the world has a lot to celebrate.

With a net worth of about $148 billion, according to the Bloomberg Billionaires Index, Ballmer is now just shy of overtaking his old boss, Microsoft founder Bill Gates, who sits at $154 billion.

A look back at Ballmer’s illustrious career reveals the secrets behind his success, but it wasn’t always so glamorous. At 24, Ballmer dropped out of Stanford Business School to join Microsoft and Gates, his former Harvard classmate. As the company’s 30th employee, Ballmer netted a base salary of $50,000.

The small tech startup quickly became one America’s fastest-growing companies, overtaking the incumbent Apple and dominating the growth of personal computers in the 1990s by developing Windows, an easy-to-use operating system. Ballmer took over for Gates during a key moment of transition, in 2000, managing through the aftermath of a famous antitrust case that dated back to 1998, as well as the aftermath of the dot-com crash and the emergence of fierce competition from rivals both new and old: Google and Apple.

Ballmer tripled Microsoft’s annual revenue to nearly $78 billion during his tenure, and profits swelled to $22 billion during his last full fiscal year as CEO, but the stock didn’t reflect its dominance. In retrospect, Ballmer set the stage for a stunning comeback in the decades since. Microsoft now ranks 13th on the Fortune 500, while its market capitalization has conquered all others: It’s the most valuable company in the world, at $3.2 trillion.

Ballmer still holds an estimated 4.5% stake in Microsoft, and has seen its value soar even further, following his successor Satya Nadella’s bet on OpenAI. In 2021, Ballmer became the ninth person in the world to report a net worth of more than $100 billion, and Ballmer is the only centibillionaire to make his fortune as an employee, not as an entrepreneur.

After thanking employees for the “time of my life” in an emotional farewell presentation in 2014, Ballmer set his sights on other entrepreneurial adventures. The same year, he bought the NBA’s Los Angeles Clippers for $2 billion (Forbes now values the franchise at over $4.5 billion).

Since leaving Microsoft, Ballmer has leaned heavily into philanthropy. He donated nearly $2 billion to a donor-advised Goldman Sachs Philanthropy fund focused on economic mobility in 2018. More recently, he invested $400 million to support Black-owned businesses in 2022; $43 million in the early childhood education workforce in Washington State last March; and last September he announced a $175 million investment over the next seven years, aimed at helping 4 million young people, especially in communities of color who face systemic inequalities, along the path to economic mobility.

In one of his final interviews as Microsoft’s CEO in 2013, Ballmer sat down with Fortune to share some of his biggest tips for success.

1. Take a look at the big picture

“If the CEO doesn’t see the playing field, nobody else can,” Ballmer said in the 2013 interview with Fortune. “The team may need to see it too, but the CEO really needs to be able to see the entire competitive space.”

Microsoft’s variety of products, like cloud services and personal computing, touch a lot of different markets and competition seems to lurk around every corner. During his stint as CEO, he faced criticism for not adapting quickly enough to changing market trends. Competitors in mobile devices, like Samsung and Nokia, and cloud computing services, like Google and Apple, were on the rise. Microsoft’s stock was stagnating in the years leading to his retirement in 2014. Still, Microsoft’s revenue nearly quadrupled under his watch.

2. Always look for talent

While at Microsoft, Ballmer hired some of the biggest names in Silicon Valley, like Steven Sinofksy, who headed Windows; J Allard, who served as chief technology officer of Xbox; and Ray Ozzie, Microsoft’s chief software architect.

In a 2009 interview with the Wall Street Journal, Ballmer said in order “to be dynamic,” companies should aim to promote internal workers “70% or 80% of the time,” and when a company wants to take on outside hires, they should be “open-minded” and ask for references.

In interviews for potential new hires, the two biggest qualities he looks for are passion that he “can see in the eyes,” and someone he can relate to. One of his favorite questions to ask is “tell me about something you’re proud of.”

3. Always reconsider–that’s how to find the most successful business model

At Microsoft, the name of Ballmer’s game was rethink, rethink, rethink.

“There was a day when people said all the money is in software; get out of hardware,” he told Fortune in 2013. Hardware was what Apple and Samsung, Microsoft’s biggest rivals at the time, were also profitable in. In 2013, Apple recorded 170.9 billion in revenue. Google recorded $55.5 billion. “Then somebody will say, ‘oh, it’s all about advertising,’” which is what its rival, Google, was making bank on.

“The playing field is always changing,” he said, and the sentiment holds true in his current endeavors on the basketball court.

A decade after buying the Clippers, Ballmer is still thinking creatively about how to revamp the franchise. He’s been signing–and retaining–superstars like Kawhi Leonard, Paul George, and Russell Westbrook to form a quartet of stars in preparation for the Intuit Dome grand opening in August, Forbes reported, the team’s future home court and the setting of the 2026 NBA All-Star weekend.

This month, he launched a new brand, Halo Sports and Entertainment, which will feature the new dome, the LA Clippers, their G-league affiliate team called the Ontario Clippers, and KIA Forum, a music and entertainment arena in Inglewood, which he purchased in 2020.

4. Plan for the short term and long term

“Getting the big things right that make all the money, that’s long cycle,” Ballmer told Fortune in 2013, emphasizing that “really executing in a way that allows you to do it, that’s short cycle.”

One of the long-term projects he’s chipped away at is USAFacts, a database that collects and analyzes how federal, state and local governments generate revenue and spend money. The database also includes reports users can run to gather information on topics ranging from tax rates to rates of overdoses and crime across the country.

The site brands itself as a “non-partisan, not-for-profit civic initiative,” with no “political agenda or commercial motive.”

5. Know where you fall short

“I obviously understand the business stuff better than the technology stuff,” Ballmer concluded in the 2013 interview, but adding, “I’ve grown, and when you grow, you say, ‘Wow, I didn’t know what I didn’t know.’”

One joke theory related to his limitations has cropped up: it’s what Urban Dictionary calls the Ballmer Peak, or the “theory that computer programmers obtain quasi-magical, superhuman coding ability when they have a blood alcohol concentration percentage between 0.129% and 0.138%.” The theory is loosely tied to Ballmer—but has inspired a San Francisco organization, Originate, to organize a Ballmer Peak-A-Thon: an open bar event where people have “5 hours to find the elusive Ballmer peak, and build the best worst business possible.” The bar provides “plenty of sill domain names” to kick off the party.