Our choices are no longer guided by pleasure or good sense but by the words 'good for our health', so taking a walk has turned into a fundamental need, as it oxygenates the brain, tones the body and protects us against diabetes, cancer and depression. This is, of course, provided that we do it daily for at least half an hour at a sustained pace. This is exactly how a spontaneous act becomes an obligation. We no longer talk about lettuce salad, a tomato, a yogurt or a glass of wine, but omega-3, antioxidants and probiotics.