For ecstasy, read relief.

When Barack Obama triumphed in the 2008 US presidential elections, he carried with him into the White House a sense of infinite possibility. The very idea that a black man bearing the middle name Hussein could rise from obscurity to become the world's most powerful leader suggested that the American Dream was alive and kicking. In that moment the whole world seemed to share the mantra of "hope" and "change" that he had sold so successfully to the electorate.

Four years on, a greyer more care-worn President Obama greeted his supporters after his re-election. Among those who have championed him, including this newspaper, relief replaces the ecstasy of 2008. In his victory speech he restated the American exceptionalism that he so embodies: the belief that "you can make it here in America if you are willing to try".

Yet here is a country that has not been transformed by the Obama presidency. Hope and change were soon engulfed by the worst economic crisis since the Great Depression. It is a US that feels as if it is in recession, even if the figures suggest otherwise, a US where wealth has been concentrated in even fewer hands and social mobility is waning.

Of course, given the awful economic legacy of the Bush era, the high hopes that accompanied his accession were absurd. And much of the non-achievement of the last four years must be put down to the obstructionism of his Republican opponents in Congress and an American Constitution so weighed down with checks and balances that it hampers bold government. Even so, Mr Obama has lost much of his lustre. Competent is perhaps the best description of his first term performance.

The fact that the electorate has decided to give him four more years must be as much a reflection of the failings of his opponent as the President's strengths. The contradictions of the Republican campaign were reflected in their candidate. As Governor of Massachusetts, Mitt Romney was a bipartisan moderate but in his anxiety to placate Tea Party right-wingers he proclaimed himself "severely conservative". As governor he championed the model for Mr Obama's health reforms, which he threatened to repeal as President. His professed worship of "small government" looked like an own goal when Superstorm Sandy necessitated precisely the sort of Federal intervention he would have cut.

In his gracious concession speech, Mr Romney spoke of the need to "put people before politics". A period of introspection is now in order for the Republicans. They need to decide whether to retreat into being that small state right-wing party of tax and welfare cuts that attracts the votes of white working men or reach out again to the middle ground and the ethnic minorities, as George Bush Jr and Ronald Reagan did. In a country where the white electorate declines by 2% every four years and the Latino one expands by 2% every two years, that looks like a no-brainer. Centrist Republicans should be able to appeal to the immigrant work ethic and family values.

This is about more than simple demographics. Politics is about the art of the possible. That requires negotiation and compromise. Yet Mr Obama returns to virtually the same political arithmetic in the Senate and House of Representatives that has hamstrung almost every political move he has made. The Senate still lacks the 60-seat majority required to force through Democrat legislation and Republicans retain a sizeable majority in the House of Representatives. Having failed to unseat Mr Obama, the Republicans must now be prepared to do deals in the national (and international) interest.

On top of the in-tray is "the fiscal cliff", the collision of expiring tax breaks and public spending cuts. Mr Obama must use it to get leverage over House Republicans to do a deal for more stimulus, raise taxes on the wealthy and cut unnecessary spending. At the same time he must avoid cutting help for the poorest, which would increase inequality further.

Reform cannot stop there. It is 25 years since Mr Reagan cleaned up the tax code, pruning away loopholes. It is time to get the fiscal shears out again. Tax reform should form part of any long-term deficit deal.

And progressive healthcare reforms, which would have been threatened by a win for Mr Romney, can now be nailed on more firmly by a second-term Mr Obama.

Knowing he will not face the electorate again frees him to concentrate on his legacy. Climate change barely got a mention in a campaign where both candidates painted themselves as friends of coal. But coal is the villain of the piece in man-made global warming. In 2008 he described climate change as "an economic albatross and a moral challenge of our time". That remains true. Whether it is by taxing carbon or boosting green energy, the US must stop dragging its feet.

American presidents often look to foreign policy for their legacy. Mr Obama could use his second term to attempt to earn that premature Nobel Peace Prize by working to bring together Israel and the Palestinians, to date an area of disappointment. Meanwhile, he must continue to work for a diplomatic solution to the Iranian nuclear crisis and an end to bloodshed in Syria.

In a recent poll of 20 countries, only Pakistan came out in favour of Mr Romney's candidature. Little wonder. It is a profound mistake to pretend US drone strikes are a substitute for a coherent policy in the Afghan-Pakistan border region when every civilian casualty acts as a recruiting sergeant for the jihadists.

At home and abroad, there are deals to be done. If he can negotiate the fiscal cliff, there is 3% growth in prospect next year, which the UK can only dream of. That is a better situation than Mr Obama inherited in 2008. No incumbent since Franklin Roosevelt has held on amidst such bad figures. "Big government" FDR remains perhaps the greatest US president of the 20th century. That should be a good omen for Barack Hussein Obama.

As Henry Adams once put it: "Nothing is more tiresome than a superannuated pedagogue." That epithet is worth remembering in the week I qualify for the state retirement pension. Joy at the prospect of never ever again paying National Insurance (thanks to being at the fortunate end of the monstrously unfair women's pensions transition process) is tempered by a terror of morphing into a wittering wrinkly, forever lambasting the young and longing to turn the clock back.

What better way to celebrate this minor milestone than by looking forward to what, God willing, could be a long and fulfilling old age? In Derbyshire this week, Reg Dean was chalking up an altogether more impressive red letter day: his 110th birthday. Reg turned 50 the year after I was born, which puts my incipient OAP status in perspective. As Britain's oldest man, this retired vicar attributes his longevity to laziness and a revolting brown potion once prescribed to him by a doctor in Bombay.

Writer and explorer Dan Buettner, who has studied centenarians for years, reckons there are five "Blue Zones" where centenarians are two-a-penny and living to 90 is normal. They include the Greek island of Ikaria, Okinawa in Japan and the Barbagia mountains of Sardinia. He concludes that there's no single secret to long life. Rather it is a combination of good genes, hard work, plenty of exercise, a healthy diet and a supportive culture.

Scotland must be in the Red Zone. A recent report from the National Records of Scotland, based on the 2001 Census, calculated that, although there has been a 43% growth in centenarians since 2002, Scotland still lags behind the rest of the UK (with 12,000 aged 100-plus), on account of generally lower life expectancy. Even so, there are at least 820 Scots with a three-digit age (that's about 1.6 per 10,000), including 40 aged 105 or more. Because of the post-First World War baby boom, these numbers will shoot up in a few years' time.

In late 1999 I travelled Scotland seeking out sentient centenarians for a feature about those who, come the millennium, would have lives that had spanned three centuries. When I look back on the highlights of my journalistic career, encounters with Kris Kristofferson and JK Rowling will pale beside the afternoon I spent in Alyth with 103-year-old twinkly eyed Alfred Anderson, who cooked for himself and hopped on a mobility scooter to visit his 80-year-old daughter in a nearby Eventide home. Or Chrissie McLaren (4ft 10ins) in Banchory, who had finally stopped digging potatoes and chopping her own wood at 102. Or gentle Alex Thomson in Ayr, who dandled his latest great granddaughter, made his own furniture and went for four-mile walks.

Or Salvation Army sergeant May Ramage, still eagerly devouring each copy of the War Cry and worrying about refugees in Kosovo. Or Lizzie Crawford, a miner's daughter, who celebrated her centenary in a superb Frank Usher outfit and told me: "I'm saving up for the second hundred years!" These lords and ladies of life, alas now all dead, lived each day as if it were their last. A sensible strategy, given that only around 60% of centenarians reach 101.

Each of "my" centenarians had known terrible hardship: holey shoes, watered-down soup, the long shadows of two world wars. Yet it was hard to envisage a bunch of people more different from Shakespeare's pathetic seventh age of man ("sans teeth, sans eyes, sans taste, sans everything").

Though thoroughly supportive of the NHS to treat others, they had rarely used it themselves. Rather, in a near magical way, these chirpy, vigorous, adaptable, curious people seemed to have outlived old age and brought a whole new meaning to the term "great age". There was a radiance about them and, despite the breathtaking pace of change in the 20th century, they absorbed it and continued to look forward. In Japan, where the old are venerated, Alfred, Chrissie, Alex, May and Lizzie would have been feted. Instead, they lived in quiet obscurity, getting on with life without grumbling. And not a superannuated pedagogue between them.