In the early 2000s, the Ford Motor Company was struggling. Badly. In 2006, it posted a loss of $12.7 billion--a staggering number. It was the kind of number that prompted big  changes, one of which was bringing in a new president and CEO: Alan Mulally.

Mulally went to work. By 2010, Ford's net income had increased to $6.6 billion. Its stock has now appreciated over 1,000 percent from its recession lows. Mulally successfully stewarded the company back from the brink of disaster, helping make it the only major American car manufacturer to avoid a government bailout.

This remarkable turnaround is one of the reasons Mulally made No. 3 on Fortune's list of World's Greatest Leaders, is listed as one of Barron's World's Best CEOs, and was Automotive News magazine's Industry Leader of the Year.

So how did he do it? What was the source of the transformation? What did Mulally use to take a massive, entrenched company from failing spectacularly, to outperforming practically every single other major company in its industry?

In a word, love.

In 2006, just after becoming CEO, Mulally made a speech to 4,000 Ford employees--corporate workers and car dealers alike. At the end of the speech, he had the entire executive team stand up and turn around to face the dealers. Then he asked them to do something very specific: He told them to tell the dealers they loved them.

They didn't do it well enough for him the first time. So he had them do it again ... like they meant it. And after that time--after the executive team had a moment to pull themselves together and get in touch with the actual feeling--the atmosphere changed.

"I felt the love," said one dealer who was there at the time, "and sensed at that moment that the culture of the Ford Motor Company had begun a transformation that would be second only to the era of the legendary Henry Ford."

Love isn't really all you need. To pull off the kind of transformation needed at the level required at Ford, you also need a plan. And, according to Mulally, you need to let everyone on the team know what that plan was.

But plans can be executed only by teams that want to work on them, and that want to work on them together. Mulally knew that without trust, teamwork, cooperation, and, yes, love, "just" having a plan--any plan--would fail.

So he put love front and center. And in a later interview, he revealed what he sees as the whole point of success:

The purpose of our success is to serve others, because that's the ultimate reward.

To serve others.

Not to gain a hundred thousand followers, or buy a super-yacht, or make the cover of all the business magazines, or any of the other external markers of success. The purpose of success is to serve others, including your own employees.

The thing that is so often missed is the win/win nature of this kind of love. We tend to think of love and money as separate, as existing in different spheres. But the truth is that love is quite literally the foundation of success. Why? Because love is what brings teams together, and keeps them there. Teams that love one another are united, and united teams outperform others on all levels: physically, spiritually, and financially.

Highly successful people from every industry know this--even venture capitalists. Entrepreneur and VC blogger Hampus Jakobsson of BlueYard Capital, says, "If there's anything I've come to grasp as an entrepreneur, it's that the way to lead people isn't just to 'be there' for them--it's to love them. I love the hell out of my people, and the level of respect created as a result is very high. We trust each other implicitly, which means we can take risks together that we wouldn't otherwise."

He runs a $100 million-plus VC firm, and his business advice is the same as Mulally's, former CEO of a multibillion-dollar company:

Love the hell out of your people.

It pays off in more ways than one.