One of my patients – let me call him Robert for reasons of anonymity – has recently started going to the gym three days a week.

Now there is nothing strange in a man deciding to commence a programme of regular physical exercise and working out in a gymnasium (although I am amazed at what some of these modern gyms charge their customers for the privilege of exhausting themselves in air-conditioned comfort) but in the case of this particular patient, the news of his sudden interest in physical exercise amazed me.