The mind is just another muscle.

Every few seconds it changes - up an eighth, down an eighth - it's like playing a slot machine. I lose $20 million, I gain $20 million.

You can never quit. Winners never quit, and quitters never win.

I lost 80 percent of my wealth and then gave away over half of the rest. So I'm a man of modest means now. But if you budget carefully and watch your expenditures, you can get by on a couple billion dollars.

The next most dangerous thing [after nuclear proliferation] is probably... global warming, and then, right behind that are overpopulation -- we need to get serious about family planning-and trying to alleviate poverty, to get clean, renewable energy, probably with solar panels to the billion and a half people in the world who don't have access to electricity.

We'll be eight degrees hotter in ten -- not ten, but thirty or forty years, and basically none of the crops will grow. Most of the people will have died and the rest of us will be cannibals.

When I was young and ocean-racing competitively, and working the rest of the time, I was going 24 hours. I was on the verge of collapsing. But you've got to slow down a bit.