Hills, hips, dark lanes, prams and when to check with a GP

The rule holds everywhere, but some bodies and some places need their own paragraph.

Joints. If knees, hips or ankles complain, the NHS advice is to increase walking distance gradually, and to look at swimming pool exercise classes if joints are a problem, because the water supports them. Set the line at half a mile and one floor, keep it there for a month, and move it when the joints have stopped commenting. Downhill is harder on knees than uphill, and a stick on a steep route isn't a defeat.

Breathlessness and chest pain. Stairs are vigorous, and being out of breath at the top of two floors is normal for a person who's been taking the lift for years. Being unable to speak at the top, or feeling faint, or any pain in the chest, arm or jaw, isn't, and it's a GP appointment. Chest pain that doesn't go away when you stop, or that comes with sweating, sickness or breathlessness, is 999, and I'd rather you rang and were wrong than didn't.

Hills. A hill on the way to the shop is a reason to walk slower, not to drive. At the talking pace you'll arrive later and no warmer. If the hill is steep enough that you can't talk, you've found the vigorous version of the errand walk, and you can do it at whatever pace lets you talk.

Disability and age. The line is yours. If a mile isn't possible, the argument holds at whatever distance is, and the errand walk that's two hundred yards to the corner is the same argument as the mile. Set it with a GP or a physio if you'd like a second opinion. What the book objects to is legs that could and don't, not legs that can't.

Dark lanes and no pavements. Some routes aren't safe on foot, especially after dark, and chapter 10 said so. A road with no pavement, no lights and fast traffic is a reason you'd say out loud, and you should say it and drive. What I'd ask is that you check whether the route you've been driving is that, or whether it's a route you've never walked and assumed. Many are the second. And there's often another way, on foot, that the car can't take, between the houses or through the park.

Prams and small children. A pram is a walking aid, in effect, and a child in one is a child being walked. The mile is longer with a toddler who wants to look at every gate, and the line for those trips can be half a mile for a year or two. They grow.

Rural. If the nearest shop is four miles away, the line doesn't reach it, and that's fine. The rule still applies to the village, the school if there is one, and the far end of the car park in town. And a mile of country lane is a better walk than most towns can offer.

Cycling. Everything in this book applies with a bike to trips of up to three or four miles, and the evidence in chapter 12 on active commuting covered cycling as well as walking. A bike moves the line out. That's a book of its own and I'll leave it there.

Winter. The line doesn't change. The coat does. If the pavements are iced, that's a reason you'd say out loud, and it happens a few days a year.

The reader who can't. If you've read this far and the honest answer is that walking a mile isn't something your body can do just now, for any reason, then the book isn't about you, and I'd rather say that plainly than have you feel judged by it. Talk to a GP about what distance is right, set the line there, and take what applies.