When my siblings and I would help ourselves to large servings of food, my father would often ask, “Are your eyes bigger than your stomach?” It was his way of teaching us to pace ourselves. There was abundance—more than we could eat, which meant that if we took modest helpings and finished them, we could always have more. His fear was that our oversized portions would result in waste.

That lesson often comes back to me when I’m helping a team set their “Rocks” (90-day goals) for the upcoming quarter.

We call them Rocks in reference to Stephen Covey’s analogy about managing time—that you’re trying to fit rocks, pebbles and sand into a jar. We always put the small stuff in first, but it fills the jar more than halfway up so there’s no room for the rocks. It turns out that the only way to fit it all in is to put it in the other way. Put the big stuff in first and let the small stuff fit in around it.

Rocks are the big, important priorities that you should be working on first. You need to fit them in along with all your day-to-day responsibilities.

The problem I encounter most often when teams are setting Rocks is that those teams are filled with overachievers. This isn’t a surprise. One of the ways people get promoted, especially in entrepreneurial companies, is by showing that they’re willing to take on more than anyone else. Back to Dad’s catchphrase—if you’re a leader in an entrepreneurial business, you’ve probably been rewarded your entire career for “overeating” when it comes to setting goals.

The EOS rule is that a leadership team should set 3-7 Rocks for a quarter, and that each member of the team should set 3-7 for him/herself. I routinely see teams and individual members aim for the high end of that range, and it’s not uncommon to see people break through it and take on 8 or more Rocks for the next 90 days.

The problem with this is that the more Rocks you set, the fewer you get done, and the fewer still that you get done with excellence. Historically, it turns out that most teams and most people can, at best, do an excellent job of achieving 3 goals at any one time. Beyond that, returns usually diminish. Set 4 Rocks and you’re likely to get 3 done, only 2 with excellence. Set 5 and you might get 2 done, 1 with excellence.

Taking on more may make you feel like a hero, but what you’re really doing is slowing yourself down. Rocks that aren’t completed will slop over into the next quarter. Rocks that are completed without excellence will require more work at some future point. Teams that commit to a small number of critical priorities every quarter and get them done with excellence build on success. Over time they move much faster.

Hewlett-Packard co-founder David Packard once said that “Organizations are more likely to die of indigestion than starvation.” He was right, and so was Dad. Our eyes often are bigger than our stomachs. There will always be more to do than you have the people, money and time to do—more food on the table than you can possibly eat. Your challenge as a leader is to decide which of those priorities are critical now—which ones are truly deserving of your time, energy and excellence.

Deciding which ones to not do, or at least not do now, is difficult but essential because less really is more.