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By Lisa Tolin

Here’s some welcome advice for anyone putting in long hours to get ahead at the office: Stop.

That’s according to Morten Hansen, a management professor at U.C. Berkeley who has made it his mission to find out what leads to better performance at work.

Hansen led a study of 5,000 people working different types of jobs — from factory floor workers to senior managers in the corner office — to find out just what made the difference in their performance.

“The main finding, and it's actually a huge surprise to me, is that the best performers, they do less,” Hansen told NBC News BETTER. “We always think about the opposite, right? The best performers should be those who are on 24/7, they are juggling five, six, seven, eight projects at the same time. They go to meetings after meetings. But no, the best performers, they were able to prioritize and to concentrate on a few things that really matter for performance.”

Working longer hours does lead to better performance up to a point: about 50 hours a week. After that, the quality of work levels off and deteriorates, Hansen explains.

Of course, just working less won’t make you a top performer. Hansen says the best workers also hyper-focus. He calls this “do less, then obsess.”

It’s among seven principles of mastering your performance that Hansen has identified in his new book, “Great at Work: How Top Performers Do Less, Work Better and Achieve More.”

1. Do Less, Then Obsess

Hansen’s research showed a clear advantage for those who focused on a few key priorities instead of a wider range of job functions — an advantage his team calculated as a 25 percent improvement. Finding focus takes a certain amount of self-discipline, as well as an ability to say no to bosses and colleagues.

"Here's a tip to improve your performance right away: Write down your priorities on a piece of paper, and maybe 10. Then you take your pen, and you cross out the bottom seven, and you say, I'm gonna focus on the top three," he says. Find ways to postpone, delegate or rethink the other seven.

2. Redesign Your Work

Focus is important, but how do you make sure you’re focused on the right thing? “You have to start a job saying, what are the things that I can do that create the most value?” Hansen says. And if you do that, it might just change your job description.

3. Don’t Just Learn, Loop

Hansen calls the most effective feedback system a “learning loop” — try something, get feedback, modify your actions, then try again. For example, if you run a weekly meeting, ask someone to attend a session and evaluate your effectiveness so you can change your presentation next time.

4. P-Squared (Find Passion and Purpose)

Finding passion at work isn’t just about following your bliss. Hansen’s research found that passion wasn’t limited to certain types of jobs. For some, finding joy meant savoring relationships with colleagues or customers.

The important thing is marrying that passion with a sense of purpose: “Purpose is, do what contributes to others. Purpose asks what can you give the world?”

5. Be a Forceful Champion

You can’t just count on everyone falling in line with your brilliant idea. Conventional wisdom is that you need charisma to change minds. But Hansen calls that “dead wrong.” People who use demonstrations, persuasive arguments or coalitions can also turn colleagues into collaborators.

6. Fight and Unite

Hansen says most businesses are doing meetings all wrong. “I mean, let’s face it, people hate going to meetings,” he says, noting that 69 percent say they find meetings unproductive. He advocates using meetings to bring together a diverse group of people to argue, then uniting behind whatever decision is made.

“Meetings should be for one thing, and one thing only, and that is to have a rigorous debate among the people in the room,” he says. “If you have a status update, you just want to share information? You should put that in an e-mail.”

7. Disciplined Collaboration

Some people collaborate too little. Some do too much. Both are problems, Hansen says.

Under-collaborators sit in their own department and don’t talk to others. Over-collaborators do everything together, going to too many meetings and wasting time. “Both are sins,” he says. “They don’t produce value. They’re wrong ways of working.”

NEXT: How to stop being so busy and get more done

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