Since our culture loves to talk about inspirational and highly visionary leaders, you might suspect that I’m going to tell you the most important thing a leader can say is something to the effect of, “Yes, we can.”

Actually, the opposite. “No” is a leader’s most powerful tool.

It’s how you keep a team on course, focused on what matters most. It’s everything from the micro to the macro, including:

●      I’m not going to go to that meeting, because it’s not as important as other priorities

●      I will make a tough decision and stick with it, even though it upsets or disappoints people about whom I care deeply

●      I’m not going to have a dozen direct reports any longer, even though no one wants to come off the leadership team

●      I’m not going to allow us to work six projects simultaneously, in a misguided effort to “reduce risk”

Once you put forward a vision and get people to rally behind it, your most important task is to build forward motion and guard against everything else: diversions, shiny objects, diffusion of focus, and the tyranny of a chaotic world.

Here are a few tips that can help keep you on course:

First, don’t hesitate to make hard decisions and stick with them. That’s the mark of being an effective leader. Real choices. If you are clear and consistent with your logic, it is possible to deliver news that people may not want to hear and still have them buy-in.

Second, leverage systems that put the priorities front and center for your team. Have a way to remind people day after day, week after week, what is most important. Screen out or minimize everything else. (If you lack such a disciplined system, you can’t blame team members when they stray off course.)

Third, exercise personal discipline. This both maximizes your own impact as well as models the right behavior for others. Focus your attention on things that make the highest and best use of your own skills, and to the greatest extent possible delegate everything else. This has the secondary benefit of empowering your team to step up and leverage their own talents.

There are some who argue that a ‘Don’t Do’ list is far more important than a ‘To Do’ list, and in many ways I agree. Executing well requires the discipline to protect the boundaries of what matters most, and that is a leader’s primary responsibility.