Warren Buffett, when asked to describe what sets successful people apart, once said, "The difference between successful people and really successful people is that really successful people say no to almost everything."

Steve Jobs clearly agreed -- so much so that almost every day, Jobs asked then Apple head of design Jony Ive the same question:

"How many times did you say no today?"

To Jobs, saying no created focus. He didn't see being "busy" as a proxy for output, or seriousness, or productivity.

Or even drive.

Because it's easy to get plenty of things done without ever getting the one or two things that matter most done. The key is to do what will make the biggest difference.

Even if some of the things you could do sound great.

Like saying "yes" to a productivity improvement initiative when what you really need to do is channel your inner Randolph Duke and "Get back in there and sell, sell." Or saying yes to exploring a product development idea when what you really need to do is stop missing delivery dates by double-digit percentages. 

Or saying yes to a last-minute speaking gig when you should spend that time sharpening up a book proposal. (OK, maybe that's just me.)

There are plenty of things you could do.

But only a few really matter.

If you're struggling to achieve what you want to achieve, take a step back. Remind yourself what drives results.

In most cases, what really drives results is you.

(But that doesn't mean your presence is absolutely necessary in every meeting, and on every call. When you're not there, your teams naturally feel a greater sense of freedom, autonomy, and most important, responsibility. The result? They'll be more creative and make better decisions.)

Make thoughtful, smart, logical, conscious decisions about everything you do. Make every decision about how to use your time based on what will make you most successful, especially over the long term. 

Try it. Don't just mindlessly fill in the blanks in your schedule. View an open calendar as an opportunity, not a liability.

Say yes to what truly drives results.

Say no to everything else -- or at least until you've taken care of the things that really matter today

Correction: An earlier version of this column misspelled Jony Ive's last name.