"I don't have time"

This is the belief most readers will land on when the others have gone, and it deserves the best answer I can give it.

The first answer is chapter 3. For the trips this book is about, the time isn't as different as it feels, and sometimes it's the wrong way round. Time it before you decide it's a cost.

The second answer is that where there is a cost, the time isn't lost. It's moved, and it comes back with something attached. A twenty-minute walk is twenty minutes in which you can think, and the evidence is that you think differently while walking. Marily Oppezzo and Daniel Schwartz, in 2014, ran four experiments in which people did tests of creative thinking sitting down and then walking, on a treadmill and outdoors. Walking raised scores on the test of coming up with new uses for ordinary objects in most participants, and the boost lasted for a while after they sat down again. Walking outdoors gave the best results of all. The test was of the kind of thinking where you generate ideas, not the kind where you converge on one right answer, which walking didn't help. So the walk is a good place to put the problem you've been circling at your desk, and a poor place to do your tax return.

It's also a good place to put a phone call, a podcast, or nothing at all. The NHS walking page suggests music or a podcast to take your mind off the effort. I'd add that twenty minutes of nothing, on foot, is one of the few stretches of nothing left in most adult days, and people who take it tend to want it again.

And there's what the walk does to how you feel about the day. Adam Martin and colleagues, in 2014, used eighteen years of the British Household Panel Survey, with nearly eighteen thousand commuters, to look at how the way people got to work related to their psychological wellbeing, following the same people as their circumstances changed. Compared with driving, both walking or cycling and public transport went with better wellbeing on a standard questionnaire. Each extra ten minutes of walking to work went with a small rise, and each extra ten minutes of driving with a small fall. People who switched from the car to walking or cycling showed a rise larger than either. This is observational, and the effects were modest on the scale used, but the direction is the one that matters for the objection. Time spent driving isn't neutral time. It's time that goes with feeling slightly worse. Time spent walking goes with feeling slightly better. The twenty minutes you'd be saving in the car aren't free.

Mark Hamer and Yoichi Chida, in a 2008 review of eight studies with over a hundred and seventy thousand people, found that walking or cycling to work went with an eleven per cent lower risk of cardiovascular disease over the follow-ups, an effect that was clearer in women. Same caveats, same direction.

So the honest accounting is this. On a short trip, the walk costs a few minutes more than the car at most. In exchange you get twenty minutes you can think in, a small lift in how you feel about the day, and the health effect from chapter 4, and the car's few minutes come with the parking dance and a small drop in mood. The walk isn't the expensive option. It's the option that was never priced.