Often, the most visible public service is performed by those who have run for and been elected to political office. In good times, they sometimes get some of the credit. In bad times, they receive most of the blame. That's the lot of a public servant. So why do it? U.S. News asked four current and former public servants. Here's what Chuck Hagel, former U.S. Senator from Nebraska and now a professor of foreign policy at Georgetown University, had to say:

Democracies and institutions of self-governance work because of responsible citizenship. Politics is the framework and elections the process that democracies use to choose leaders. The quality of leaders and effectiveness of government are directly related to informed and committed citizens willing to participate in politics. We draw from this universe those willing to offer themselves as candidates for elective office. Elections have consequences because they produce the leaders who shape the policies that govern a democracy. Politics reflects society. Every variation of public service, including elective office, should be anchored by one complete and overriding truth and objective—to make a better world. Political office is but one way to work toward this end and offer oneself in its service.

Politics is a noble endeavor—only if it is about public service. I often tell bright young people who seek my advice on running for office: Consider it only for the right reasons and understand it will be frustrating, often unfair and negative, occasionally brutal, but always exhilarating as well as enriching, rewarding, and worth doing.

In politics you can witness courage up close, experience inspiration you never knew existed, and find opportunities to help bring consensus to difficult and divisive issues to solve problems.

Elected public servants have the responsibility to govern, to find the common interests of a society and build around them—not polarize and paralyze for base political interests. Governing is not easy, especially during times like the present when there is so much anger and distrust of public institutions, especially government and elected officials. It is during challenging times that elected officials must show the most courage. They must engage the headwinds of negative public opinion with honesty and straight talk. The two most indispensable qualities of leadership have always been character and courage.

Elected public servants must not allow themselves to become disoriented from the business of governing. Our country depends on this. Elected officials must realize they fail their country and those they represent if they succumb to the sometimes violent currents of political opinion—which they bring on themselves when they don't lead and govern with integrity.

There is always the inherent conflict between, do you vote based on your constituents' opinions, or your own conscience? This has been a central issue of democratic political drama over the centuries. The best explanation I've ever heard or read that addresses this question—one that I subscribe to—is Edmund Burke's response two centuries ago: "Your representative owes you, not his industry only, but his judgment; and he betrays, instead of serving you, if he sacrifices it to your opinion."