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.