Photograph: Antonio Olmos/The Observer

I still get funny looks from people when I mention that I keep a diary. Maybe the practice strikes them as shifty or weirdly old-fashioned. It’s true that I never feel more furtive than when my wife finds me writing it at our kitchen table – it’s like being spotted entering a confessional box in church. What exactly have I got to tell this black book about a life that we share all day, every day? What secrets can I possibly be keeping?