Make necessary modifications until you've made it better. If you take this one skill at a time, you will be able to focus until you improve.

If you're one of those people who end up clocking in 65 hours or more or week --  hoping that it will help your career --  you can forget about it.

In a new book, "Great at Work: How Top Performers Do Less, Work better and Achieve More," author Morten T. Hansen finds in a study of 5,000 managers and employees that working a lot of hours can help your performance, but only to a certain point. Specifically, if you work between 30 to 50 hours a week, adding more hours can boost your performance. But after working 65 hours or more, it's time to go home because your performance will decline.

This result if part of Hansen's effort to more fully understand what makes some people top performers. Among his findings:

It's the boss's fault. Twenty-four percent of respondents say they can't focus because the boss lacks direction or there is a broader organizational complexity in their company. But Hansen says you can learn to "manage up" and just say "no" when you need to be great in certain areas. In other words, your path to greatness isn't just about always pleasing your boss all the time.

Purpose matters. It makes sense that about 40% of the respondents from the health care fields say they believe they are contributing to society. Still, there were those in the dataset who didn't work in those fields and still found meaning in their work. For example, 28% of people working in the construction industry completely agree with the statement "You can find meaning in your job no matter what sector it's in."

High achievers don't lose focus. While other people might be piling on tasks because they say "yes" to everything, high performers are more selective. They aren't afraid to say "no" to things that won't let them devote proper attention to their tasks and do excellent work.

Challenges are important. While many people just follow a job description, top performers challenge the job description. Instead of focusing on how to do the job description well, they think about how they can create the most value out of the role. This means they may change part of the work to add more value. For example, a factory worker in the study who was responsible for his machine output did that -- but he also went to other people and asked how his output could help them do better. They told him the one thing that he then implemented, taking him beyond his job description.

Don't let passion lead you down the wrong road. While you don't want to totally ignore your passion, you need to understand that top performers don't just chase a passion no matter where it leads. They learn to match their passion with a strong sense of purpose, doing work that contributes value. They focus on the benefits they bring others and doing it well, which makes people value their work. That's what leads to a good career.

Create a learning loop. Getting in a rut and working on autopilot can kill a career. Look at things you do automatically -- such as the way you lead meetings -- and find ways to improve. Then, get feedback on your changes. Make necessary modifications until you've made it better. If you take this one skill at a time, you will be able to focus until you improve.