The MPW Insider network is an online community where the most thoughtful and influential people in business contribute answers to timely questions about careers and leadership. Today’s answer to the question:What’s the most difficult part of being a leader? is written by Sally Blount, dean of Northwestern University’s Kellogg School of Management.

Power is seductive–folk wisdom tells us so, as does a growing body of psychological research. The experience of having power changes how the brain processes information. Over the course of my career I’ve noticed when people are in positions of power, they tend to monitor their own behavior more closely and become less vigilant to the behavior and reactions of others; they listen less carefully and consider less deeply what other people think and say. They also often look to acquire things that convey and reinforce their status (i.e. desirable mates, expensive homes, and rare baubles).

Many psychologists don’t yet understand from an evolutionary perspective why this cognitive “power shift” occurs. But it’s pretty clear that the shift is hardwired and difficult to counter. It may be that when our needs were more about human survival–and less about human progress–the shift worked well for leaders. But it doesn’t serve us well in the modern world, where instilling a sense of authentic purpose and mission is more important than asserting dominance.

Today, most leaders excel when they generate positive impact for others–be it employees, customers, clients, investors, or even suppliers. They do this by successfully navigating relationships and the constantly evolving politics of large, complex organizational structures. This means that at some level, leadership in the 21st century requires paying a lot of attention to the people around you — what they are thinking, feeling, and saying. It also often means surrendering your own desires and needs for the greater good.

See also: The Secret to Becoming a Better Manager

Consider just one simple, but important example: how leaders spend their time. When you accept a significant leadership role in today’s organizations, you no longer have the same control over your calendar that you had earlier in your career. Personally, I haven’t fully “owned” my calendar for 12 years, ever since I first became a dean at NYU. These days I generally have back-to-back meetings scheduled, often through lunch and dinner. And then of course there are always the important issues and conversations you can’t plan that inevitably come up each day as well.

Keeping such a packed, fluid schedule organized and coordinated requires a lot of support. (In fact, it’s my assistant’s full time job.) And making it work means that I don’t always get to decide when, what, and with whom I meet (or eat) or even which problems or tasks I work on or in what order I attack them. The same is true for every dean, president, and CEO whom I know. It can be exhausting. But when you are a leader, you have to be where and when your team needs you, whether it’s highly convenient for you personally or not.

So, in my mind, the biggest challenge of leadership lies in how leaders react to the never-ending demands of having power. Do they go with the hard-wiring of the power shift and become more self-focused, entitled, and less reflective? Do they allow the seductive “I deserve it because I work so hard” and “my time is so valuable” voices in their heads to guide their choices as they readily gather the perks, access, and pay that often accrue with power? Or do they remind themselves that leadership is a privilege and that power can be seductive? Do they constantly push themselves to be thoughtful about their choices and impact on their organization and stakeholders?

A couple years ago, I heard a banker say that “private jets are a drug; once you try them, it’s a hard habit to kick.” Having had the privilege of flying in one a few times, I get it. But, the private jet comment always reminds me that the true challenge of leadership lies in resisting the urge to let yourself, your comfort, your status, and your ideas become increasingly important in your own eyes.

Great leadership requires overcoming the power shift–overcoming the hardwired tendency to take up disproportionate amounts of airtime in meetings. And when you do talk, it means resisting the urge to offer your views and opinions first rather than asking questions to probe and better understand the perspectives and experiences of the other people in the conversation. It means overcoming the compulsion to spend your time and your organization’s money in ways that convey or reinforce your status, rather than your impact. In short, it means measuring your success by how your people and your organization performs, not by your pay, your words, or how you fly.