From 18 to 22, I was alone, living in L.A. with a bunch of friends, partying.

We talk a lot on 'Biggest Loser' about how fitness is a natural antidepressant, how it burns off stress. What I like about running is that it gives me time alone. I'm always busy, with people at work, with my kids. I love getting out for a run by myself and just listening to my music.

Britain, relative to the U.S., is a highly secular society. Philanthropy alone cannot fill the gap left by government cutbacks. And the sources of altruism go deep into our evolutionary past.

As a young man, even if I was going to see a play or a film by myself, I didn't feel like I was alone. There was something that was unfolding up there that brought me into it. And I recognised that. For those two hours, it made me feel like I belonged to something really good.

Solitude, though it may be silent as light, is like light, the mightiest of agencies for solitude is essential to man. All men come into this world alone and leave it alone.