I've come to embrace the notion that I haven't done enough in my life. I've come to confirm that one's title, even a title like president of the United States, says very little about how well one's life has been led. No matter how much you've done or how successful you've been, there's always more to do, always more to learn, and always more to achieve.
Al Qaeda is still a threat. We cannot pretend somehow that because Barack Hussein Obama got elected as president, suddenly everything is going to be OK.
So I analyzed that and decided I didn't want to be the president during a depression greater than the Great Depression, or the beginning of a depression greater than the Great Depression.
One of the things I learned as president is that your life is just not going to unfold the way you want it to. There will be surprises, challenges, and therefore the question is how you deal with the unexpected.