It is possible to work fewer hours without hurting your career, but you need to get serious about systematically changing how you approach your work. First, don't blame your long hours on your boss, your CEO, or your underlings. Someone who does not make a conscious, organized effort to take responsibility for the number of hours they work can be thrown off course by anyone. But the person who systematically follows the steps below will not be thrown off course, even by a workaholic boss in a workaholic industry.

1. Concentrate on quality of work over quantity.
The person who builds a career on doing the most work commits to living on a treadmill. The work will never be done, and you will become known among your co-workers as someone who never turns down an assignment. Read: dumping ground.

Quality is what matters: people don't lose a job for not working unpaid overtime, they lose a job for not performing well at the most important times; and a resume is not a list of hours worked, it is a list of big accomplishments.

2. Know the goals of your job.
You need to know the equivalent of a home run in your job. Get a list of goals from your boss, and understand how they fit into the big picture. Judge if your work is high quality by what people need from you and how they measure success. Be sure to get goals that are quality oriented and not hours oriented. Suggest replacing, “Devote eight hours a week to cold-calling” to “Find six qualified leads in three months.”

3. Refuse bad assignments.
Figure out what matters, and spend your time on that. Once you have clear short-term and long-term goals, it's easy to spot the person you don't need to impress, the project that will never hit your resume, or the hours worked that no one will notice.

And then say no. Constantly. The best way to say no is to tell people what is most important on your plate so they see that, for you, they are a low priority. Prioritizing is a way to help your company, your boss and yourself. No one can fault your for that.

4. Know your boss's goals.
Your best tool for saying no to a project is reminding your boss what her goals are. If she cannot keep track of her own goals, help her. Because if you worm your way out of work that doesn't matter to her, so that you can do work that does matter to her, she is more likely to back you up. Also your boss will protect you from assignments from other people if you show her how the other peoples' work affects your boss's goals.

5. Take control of what you can.
Even small efforts at control add up to a lot, and best of all, they usually go unnoticed by others. For example, refuse to make meetings on Monday and you are less likely to have to prepare for meetings on the weekend. Refuse meetings after 4:30 p.m. and you are less likely to miss dinner at home. Ignore your phone while you write your weekly report and you're less likely to stay late to finish it. You don't need to tell people: “My policy is no meetings at x time.” Just say you're already booked and suggest another time. You can't do this every meeting, but you can do it enough to make a difference in your life.

6. Know your own boundaries.
“Wanting to work fewer hours” is too vague a goal because you won't know which hours to protect. Try getting home at 7pm, not working weekends, or leaving for two hours in the middle of the day for a yoga class. These are concrete goals for cutting back hours.

7. Be brave.
Brave people can say no when someone is pushing hard, and brave people can go home when other people are working late. The bravery comes from trusting yourself to find the most important work and to do it better than anyone else.