“Today, having come far in our own historical journey, we must decide. Will we turn back, or finish well? Before history is written down in books, it is written in courage. Like Americans before us, we will show that courage and we will finish well. We will lead freedom's advance. We will compete and excel in the global economy. We will renew the defining moral commitments of this land, and so we move forward, optimistic about our country, faithful to its cause, and confident of victories to come.”

Nelson Mandela on Aids, 46664 Concert, Tromso, Norway (11 Jun 2005). Source: From Nelson Mandela By Himself: The Authorised Book of Quotations © 2010 by Nelson R. Mandela and The Nelson Mandela Foundation http://www.nelsonmandela.org/content/mini-site/selected-quotes
2000s

2000s, 2001, First inaugural address (January 2001)
Context: We must live up to the calling we share. Civility is not a tactic or a sentiment. It is the determined choice of trust over cynicism, of community over chaos. And this commitment, if we keep it, is a way to shared accomplishment. America, at its best, is also courageous. Our national courage has been clear in times of depression and war, when defending common dangers defined our common good. Now we must choose if the example of our fathers and mothers will inspire us or condemn us. We must show courage in a time of blessing by confronting problems instead of passing them on to future generations.

2014, Address to the Nation on Immigration (November 2014)

2000s, 2003, Address to the National Endowment for Democracy (November 2003)

Speech at the Democratic National Convention (28 August 1996) http://www.pbs.org/newshour/convention96/floor_speeches/gore_8-28.html.
Context: We Americans write our own history. And the chapters of which we're proudest are the ones where we had the courage to change. Time and again, Americans have seen the need for change, and have taken the initiative to bring that change to life.

Speech to Conservative Rally at Cheltenham (3 July 1982) http://www.margaretthatcher.org/document/104989, regarding the Falkland Islands War.
First term as Prime Minister
Context: When we started out, there were the waverers and the fainthearts. The people who thought that Britain could no longer seize the initiative for herself. The people who thought we could no longer do the great things which we once did. Those who believed that our decline was irreversible—that we could never again be what we were. There were those who would not admit it—even perhaps some here today—people who would have strenuously denied the suggestion but—in their heart of hearts—they too had their secret fears that it was true: that Britain was no longer the nation that had built an Empire and ruled a quarter of the world. Well they were wrong. The lesson of the Falklands is that Britain has not changed and that this nation still has those sterling qualities which shine through our history. This generation can match their fathers and grandfathers in ability, in courage, and in resolution. We have not changed. When the demands of war and the dangers to our own people call us to arms—then we British are as we have always been: competent, courageous and resolute.

Quoted in "Pacific Affairs" - Page 51 - by University of British Columbia, Institute of Pacific Relations