"I'll buy a standing desk"

Once you've accepted that the sitting is a problem, the tempting next step is to buy something. A desk that goes up and down costs a few hundred pounds, arrives in a box, and looks like a solution. Some readers will have ordered one before finishing the last chapter.

It might help. In the Edwardson trial, the offices that got height-adjustable desks cut their sitting by about three times as much as the offices that got coaching alone. The desk made sitting less the easy option. It also acted as a reminder, because it's hard to forget you meant to stand when the handle is in front of you. If your employer offers one, take it.

But I'd like you to be clear about what the desk does, for two reasons.

The first is that standing isn't moving. Your legs do more when you stand than when you sit, because they're holding you up, and that's worth having. But someone who stands motionless at a raised desk for three hours has swapped one fixed position for another. People whose jobs keep them standing all day, such as shop staff and hairdressers, don't report that their legs and backs feel wonderful. Bodies do badly held in any one position for long. What helped in Dunstan's laboratory was walking for two minutes. If you get a desk, change position often, and walk to the kettle as before.

The second reason matters more to me, because it's about how these projects fail. Buying the desk feels like having dealt with the problem. There's a well-known way this goes. The desk arrives, you stand at it for most of the first week, your feet hurt, and by the second month it stays in the down position with a plant on it. Nothing's wrong with the desk. It was asked to do a job that only a habit can do.

So buy one if you want, but don't wait for it and don't let the purchase stand in for the change. Everything in this book can be done with the furniture you have. A worktop or a high shelf will hold a laptop for a twenty-minute standing spell. A phone call needs no desk at all. The break every half hour costs nothing and would be needed just as much if you owned the best desk in the catalogue.

The same goes for the other things sold to people with desk jobs. A better chair, a cushion, a footrest and a wrist support may each make sitting more comfortable. None of them is a bad thing to own. But a more comfortable chair is one you'll stay in for longer, and the length of the sit is what needs to change.

Watches and phones that buzz when you've been still for an hour are a partial exception, because they address the real difficulty, which is that you don't notice time passing in a chair. If you have one, switch the reminder on. If you haven't, a kitchen timer does the same job for a fiver, and chapter 14 suggests how to use it for the first couple of weeks.