For me, personally, the most difficult moments had to do with not just terrorist attacks, but also shootings.

I can be much more sarcastic and, I think, sometimes withering in my assessments of things than I allow to show in my public life.

Entrepreneurs embody the promise of America: the idea that if you have a good idea and are willing to work hard and see it through, you can succeed in this country. And in fulfilling this promise, entrepreneurs also play a critical role in expanding our economy and creating jobs.

Physically, I feel probably as good as I've ever felt. And I've got as much energy as I ever did. But what you feel after eight years - and I think you'd feel this no matter what, but anytime you have a big transition, it gets magnified - is time passes.

We are an American family and we rise and fall together as one nation.

I have always believed that hope is that stubborn thing inside us that insists, despite all the evidence to the contrary, that something better awaits us so long as we have the courage to keep reaching, to keep working, to keep fighting." (Victory Speech, Nov. 7, 2012)

As long as I'm president of the United States Iran will not get a nuclear weapon. I made that clear when I came into office.