Work is complicated. But employees shouldn't be confused about what to concentrate on to be successful.

That's why every leader needs to use the "five-finger rule" described in Fewer, Bigger, Bolder, the book by Sanjay Khosla and Mohanbir Sawhney.

The rule is a lesson that Khosla--who later went on to become the (very successful) president of Kraft Foods' developing markets--learned early. Although Khosla had graduated from a prestigious Indian university, he needed to work close to home to take care of his ailing mother. So he found a job as a salesman in India for the Anglo-Dutch company Unilever.

Khosla's assignment "was to peddle soaps and detergents on a handcart to mom-and-pop stores. The routine was humbling." He would "slog from one shop to another, then stand around, hoping to place products, while the proprietor waited on customers."

Despite the unglamorous nature of his job, Khosla wanted to demonstrate to his boss that he was doing meaningful work. So he prepared a big file of data--facts, figures, projections, sales--to present during his first review meeting.

But his boss was not impressed. "How many fingers do you have on your left hand?"

The answer was obvious. But Khosla hesitated when he responded. "Five," he said.

Right, said Khosla's boss. And then he explained. "Here's the point. We will decide on five things we want you to do. That's all we will measure. And I want you to put the results on one page. Five things, that's it."

That's when Khosla had a revelation about how he'd been spending his time. 

"I was going to have to stop doing a lot of things," he recalls. "By targeting only five, I was being given a strict, simple way to track his progress. My life quickly changed."

In short, Khosla's boss set him up for success--because Khosla was suddenly very clear what he needed to do to achieve his objectives.

What can every leader learn from this story?  Khosla, who has carried this early lesson through his entire career, gives this advice: "Whether you are talking about goals, directions, rules or metrics, keep the number small and focused."

As focused, in fact, as the five fingers on your left hand.