AFTER all the trouble in the economy, no one needs to persuade me of the importance of saving money for a rainy day. What is hard is actually doing it.

The standard advice is to save three to six months’ worth of living expenses  which sounds wise. But really, how are you supposed to salt away that much cash, given all the other demands on your income?

Saving is a deceptively difficult task for many people (born savers, I salute you!). Actually saving some money  let alone the thousands you might need to weather a crisis  results from a chain of habits and choices that does not, for many people, come naturally.

You may know that your job is at risk, or that your nest egg would not last you a week  and you really ought to start saving right now. But as with many other acts of self-discipline, “we have great intentions, but our follow-through is abysmal,” said David Laibson, professor of economics at Harvard, whose primary focus is people’s saving behavior, particularly retirement.