As a tennis player, or any professional athlete, our career has a shelf life. I don't want to waste any opportunities, I don't want to look back on it when I'm 45 and think I could have done a lot more.

I didn't know I could even be a professional tennis player, honestly. All this is actually very, very unexpected.

A lot of times when I'm confident and relaxed on the court, I'm going to be a pretty tough out. But when I'm not so confident and not so relaxed, I tense up and my balls fall short and everything. It just sort of unravels.

In the past, I've played where I only just rely on my serve.

I'm not suggesting that social scientists stop teaching and investigating classic topics like monopoly power, racial profiling and health inequality. But everyone knows that monopoly power is bad for markets, that people are racially biased and that illness is unequally distributed by social class.

We need to work to repeal Obamacare and replace it with the kind of health care choices that the American people want. That doesn't include government-run health care.

Before Medicare, nearly half of American seniors were forced to go without coverage because insurance companies were reluctant to insure them - making the chances of having health insurance as a senior the same as getting tails on a coin flip.

The Secretary of Defense is not a super General or Admiral. His task is to exercise civilian control over the Department for the Commander-in-Chief and the country.