Juliet Dunlop: What’s the best age for happiness?

Now that you’re 70 – happy birthday, by the way – you’re hurtling towards the buffers. You’ve peaked, I’m afraid. You’re no longer the rubber-faced rock star you used to be. You can’t get no satisfaction, or at least not so easily.

How different it was only yesterday. At 69 you had it all: the figure; the voice; the moves. Now you’re a has-been; a pensioner in a sequinned leisure suit with the complexion of a newly ploughed field. Sorry, but there it is. You’re probably deeply unhappy too – so unhappy that not even all your millions and your 46-year-old ex-model girlfriend can cheer you up. Perhaps you should just point the tour bus in the direction of Bournemouth – spend more time with the grand-kids and while away the afternoons dozing at the cricket. It doesn’t sound too bad. You just need to lower your expectations.

Because that’s the secret, apparently, to leading a contented life the older we get. According to a study by the London School of Economics, by the time we reach 69 we get the balance just right; aspirations are neither too high nor too low. And because they are not too high or too low, we’re more likely to feel happy and fulfilled. We may even be more successful. The other age when we feel most satisfied is at 23. But that’s because we believe anything is possible.

Just ask Mick. The Rolling Stones frontman was exactly that age when “I Can’t Get No (Satisfaction)” was released, transforming them, according to Jagger “from just another band into a huge, monster band …” This year, aged 69, he headlined at Glastonbury and returned to Hyde Park for a landmark concert. That’s not to say the intervening years have been terrible, but you have to admit there’s a symmetry to it all.

You see, happiness is U-shaped. Academic studies show that satisfaction is ranked highly in our twenties before falling in middle age and then rising again in retirement. People in their mid-fifties are the least content because of lingering doubts over missed opportunities and unfulfilled ambitions from their younger days.

The good news is, the older you get the less you care and so the happier you are – although worries creep in once you hit 70. But this latest study is the first to try to quantify how far our expectations exceed the reality.

It analysed the happiness of more than 23,000 people aged between 17 and 85. It found that adults in their twenties overestimate their future life satisfaction by around 10 per cent (the arrogance of youth) while those aged 68 (the wisdom that comes with age) underestimate their future happiness by 4.5 per cent. In fact, expectations decline after the age of 30, only slowly rising back up as we become better at managing disappointment. The things that drive you mad at 40 or 50 are simply cast aside as you advance into your sixties. Regret is as fleeting as the snow that falls into the river. As Burns put it: “A moment white – then melts for ever.”

It’s a pattern that seems to be repeated across the world, across socioeconomic groups and even among great apes. The mid-life crisis is something that apes, as well as humans, suffer from. Where that next banana comes from is a concern for big beasts everywhere. But Mick, now staring 70 in the face and a renewed drop in his satisfaction levels, can take some comfort in knowing that all those 23- year-olds out there are headed for a fall. According to the study, actresses Emma Watson and Kristen Stewart, who both happen to be 23, should make the most of their year. They’re just at that age when optimism is at a peak, the future is rosy and anything is possible. Turning 24 could be an eye-opener.

So, some advice, Emma and Kristen. As we all cling on through life’s ups and downs, you’d do well to remember that troughs eventually turn into peaks. You’ll have learned that by the time you turn 69. And who wants to be 23 anyway? Just sit back and enjoy the ride. Look at Mick…