How big is this decision?

One reason the loop catches so many decisions is that it treats them all alike. The sofa gets the same procedure as the career, with research, comparison, doubt and delay. A better habit is to size a decision before you start on it. Two questions do most of the sizing, and this scheme is mine.

The first is how much it will matter in a year. Some choices will have vanished by then. You won't remember which starter you ordered or which hotel you booked for a weekend. Others, like the course, will shape what your weeks look like.

The second is whether you can undo it. A sofa can often be returned, and if it can't, it can be sold or lived with. A job you've started can be left, though at some cost. Selling a house, having a child, or turning down a place that won't be offered again can't be reversed.

That gives four kinds of decision, and each deserves different handling.

Small and reversible. Menus, paint colours, which film to watch, most purchases under a sum you can name. These deserve minutes. Pick the first option that would do. If it turns out wrong, change it. It's worth putting a figure on it. Below, say, fifty pounds, you don't compare at all.

Small and irreversible. A haircut before a wedding, a non-refundable weekend away. They feel weightier than they are because they can't be taken back. But they're small, and in a year you won't care. Give them an evening at most.

Large and reversible. Moving firms, renting in a new area, starting a course you could leave after a term. These deserve proper thought, measured in days or a few weeks. They also come with a useful way out that the loop ignores. You can treat the choice as a trial. You don't have to know whether you'll love garden design. You have to decide whether to find out. And a term of the course will tell you more than another year of the spreadsheet.

Large and irreversible. These are rare, and they're the only ones that justify a long, careful process, outside advice and a night's sleep. They need a date as much as the others do, because a big decision with no date can be put off for longer than any other kind.

Some small decisions come round again and again. What to have for lunch, what to wear to work, which route to take, what to cook on a Wednesday. If you go round on these, it's worth deciding them once and letting the answer stand. Wednesday is pasta. At an unfamiliar restaurant you order the first dish on the menu that appeals and then close the menu. This can look like a lack of imagination. What it does is save the deciding for the things that deserve it, and it gives you practice several times a day at picking and then not looking back.

When you sort your list from chapter 1 this way, I expect two things. Most of what's on it will turn out to be small, reversible, or both. And one or two items that you'd filed as large and irreversible will move when you look at them again. The course feels like a decision about your whole life. In fact it's a decision about two evenings a week and three thousand two hundred pounds for the first year, and you could leave after that.

Write the size next to each item on your list. Then give each one a time allowance to match, in minutes, days or weeks. For anything open longer than its allowance, more thinking isn't likely to help, and the next chapter describes what to do in its place.