What the default costs you

I've argued the reasons. This chapter is the bill.

The distance. Chapter 5's step count, if you took it, is the first line. A person in the bottom quarter of the step studies is a person for whom the biggest gains in the evidence are still on the table, and the default is what's keeping them there. Saint-Maurice's four thousand against eight thousand is two miles a day, and two miles a day is the errand walks you're driving.

The mood. Martin's ten minutes of driving is a small fall and ten minutes of walking a small rise, and a day with four short car trips in it is forty minutes of the first and none of the second. Over a year that's a lot of small falls. You wouldn't notice any one of them. You might notice the sum, and call it something else.

The money. Short car trips are the expensive ones per mile, because the engine's cold, and the fuel, the parking and the wear are all spent on distances that cost nothing on foot. Work out what the half-mile trips in your week cost, over a year, and then look at what the walk would have cost, which is a pair of shoes.

The thinking time. Oppezzo's walkers had better ideas walking than sitting, and the walk to the shop is twenty minutes a day in which the problem you've been circling could have moved. In the car you're driving.

The neighbourhood. A person who drives everything under a mile doesn't know the streets they live in. They know the routes. On foot you find the path between the houses, the shop you didn't know was there, the neighbour whose name you'd forgotten. That's not a health cost. It's the cost of living somewhere for years without having been there.

The legs at seventy. The evidence on walking and mortality is about the long run, and so is the evidence on what happens to legs that aren't used. A person who walks to the shop at forty-five is, in all likelihood, a person who can still walk to the shop at seventy-five, and the second thing depends on the first more than most people think. The default isn't just a habit of this week. It's a policy about which body you'll have later.

And the children in the back, which is the next chapter, because it's a cost that lands on someone else.