My partner Fiona is forever asking, "Why can't you just be happy?'". But it's not that simple. In my little e-book The Happy Depressive - that's me - I advance a rather dark theory. It is that we don't really know if we've lived a happy life until we near its end.
Perhaps that's a non-believer's way of trying to stick to values that keep us broadly on the straight and narrow.
Which brings us to God. Now there's an area riddled with doubt. I was raised to believe, but soon gave it up. It flickers now and then, like when my friend Philip Gould died recently, aged just 61, and I saw the faith resonating from him, and comforting him, and in what he called "the death zone" giving him an equilibrium he lacked for much of his life.
But then my rational mind kicks in. "Where there is doubt, there is no doubt." This time, the doubt turned me against the proposition, not for it - although, as Philip used to tease, the door is never closed.
Believers in my family are convinced I will "do God" before I go. Tony Blair always said he was sure I was deeply religious deep down, but worried I might become an Islamic fundamentalist.
Full piece here, also reproduced on Campbells blog.
There's a fleeting reference to Philip Gould's faith in this Guardian interview from last year.