Welcome to the great big hangover. With the advent of 2009, the crunch starts for real.

We've been through denial, with festive shoppers racking up record-breaking sales splurges last month. Now we're moving on to acceptance. But it doesn't have to mean head-in-hands misery.

Mindset is all. How you start the year will set the template for 2009, and two scientifically backed character traits hold the key: optimism and resilience (if the prospect leaves you feeling pessimistically spineless, the good news is that you can significantly boost both of these qualities).

Faced with 12 months of plummeting economics and rising human distress, staunchly maintaining a rosy view might seem deludedly Pollyanna-ish. But here we encounter the optimism paradox. As Brice Pitt, an emeritus professor of the psychiatry of old age at Imperial College, London, told me: “Optimists are unrealistic. Depressive people see things as they really are, but that is a disadvantage from an evolutionary point of view. Optimism is a piece of evolutionary equipment that carried us through millennia of setbacks.”

Optimists have plenty to be happy about

In other words, if you can convince yourself that things will get better, the odds of it happening will improve - because you keep on playing the game. In this light, optimism “is a habitual way of explaining your setbacks to yourself”, reports Martin Seligman, the psychology professor and author of Learned Optimism. The research shows that when times get tough, optimists do better than pessimists - they succeed better at work, respond better to stress, suffer fewer depressive episodes and achieve more personal goals.

Studies also show that belief can help with the financial pinch. Chad Wallens, a social forecaster at the Henley Centre who surveyed middle-class Britons' beliefs about income, has found that “the people who feel wealthiest, and those who feel poorest, actually have almost the same amount of money at their disposal. Their attitudes and behaviour patterns, however, are different from one another.”

Optimists have something else to be cheerful about - in general, they are more robust. For example, a study of 660 volunteers by the Yale University psychologist Dr Becca Levy, found that thinking positively adds an average of 7 years to your life. Other American research claims to have identified a physical mechanism behind this. A Harvard Medical School study of 670 men found that the optimists have significantly better lung function. The lead author, Dr Rosalind Wright, believes that attitude somehow strengthens the immune system. “Preliminary studies on heart patients suggest that, by changing a person's outlook, you can improve their mortality risk,” she says.

Few studies have tried to ascertain the proportion of optimists in the world. But a 1995 nationwide survey conducted for the American magazine Adweek found that about half the population counted themselves as optimists, with women slightly more apt than men (53 per cent versus 48 per cent) to see the sunny side.

Of course, there is no guarantee that optimism will insulate you from the crunch's worst effects, but the best strategy is still to keep smiling and thank your lucky stars.

Because (as every good sports coach knows) adversity is character-forming - so long as you practise the skills of resilience. Research among tycoons and business leaders shows that the path to success is often littered with failure: a record of sackings, bankruptcies and blistering castigations. But instead of curling into a foetal ball beneath the coffee table, they resiliently pick themselves up, learn from their pratfalls and march boldly towards the next opportunity.

The American Psychological Association defines resilience as the ability to adapt in the face of adversity, trauma or tragedy. A resilient person may go through difficulty and uncertainty, but he or she will doggedly bounce back.

Optimism is one of the central traits required in building resilience, say Yale University investigators in the Annual Review of Clinical Psychology. They add that resilient people learn to hold on to their sense of humour and this can help them to keep a flexible attitude when big changes of plan are warranted. The ability to accept your lot with equanimity also plays an important role, the study adds.

One of the best ways to acquire resilience is through experiencing a difficult childhood, the sociologist Steven Stack reports in the Journal of Social Psychology. For example, short men are less likely to commit suicide than tall guys, he says, because shorties develop psychological defence skills to handle the bullies and mickey-taking that their lack of stature attracts. By contrast, those who enjoyed adversity-free youths can get derailed by setbacks later on because they've never been inoculated against aggro.

Learning to overcome your fears

If you are handicapped by having had a happy childhood, then practising proactive optimism can help you to become more resilient. Studies of resilient people show that they take more risks; they court failure and learn not to fear it.

And despite being thick-skinned, resilient types are also more open than average to other people. Bouncing through knockbacks is all part of the process. It's about optimistic risk-taking - being confident that people will like you. Simply smiling and being warm to people can help. It's an altruistic path to self-interest - and if it achieves nothing else, it will reinforce an age-old adage: hard times can bring out the best in you.

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