When David Cameron suggested introducing a 'National Happiness Index' as an alternative measure of progress to GDP back in 2010, it sounded like a radical policy suggestion. But in reality, the annual 'wellbeing data' that has filtered through from this experiment has a quaintly pointless feel to it. This year, for example, brought the game-changing revelation that we are marginally more likely to be happier than average if we are either a practicing Hindu or live in mid-Sussex.

It's hard to see how much use this can be to anyone on either an individual or a policy level. But in amongst it all, there has been one consistent and surprising finding from which people, of my generation at least, might learn a thing or two.

Happiness peaks in older adulthood, with women in their sixties and seventies the happiest people in Britain. I have my own theories about why this might be, and what women of my age can learn from our mothers' generation when it comes to contentment.

Research shows clearly that the more highly we value and pursue happiness as a singular goal, the more stressed, anxious and even depressed we become. And the kind of happiness rat race that this describes is a very much a feature of young adulthood.

Like many people, my twenties and thirties felt like a scramble to pin down the happiest possible life, working punishing hours to develop my career, scouring the available pool of men for a reasonable prospect to father my kids, then struggling to just squeeze those kids in, in a photofinish with the end of my fertility. I was so busy chasing and chewing over my imagined happy-ever-after that I barely had time to stop and appreciate the happiness I was experiencing along the way.

In this fug of stress, many Generation X-ers scramble to adopt whatever is the latest happiness fad to ease the pressure - from gratitude journals to yoga, mindfulness colouring to befriending our inner chimps. But when the self-help books promise "total transformation" it can leave us doubting the people we are at the moment, and lock us into a dreary cycle of self-reproach and self-improvement.

In contrast, by the time they reach their sixties, most people know the basic parameters of their lives, and can just get on with actually living them. Most of the big decisions have already been made, freeing up a huge chunk of brainspace previously allocated for agonizing and overthinking. This is a life-stage in which people have the experience to be realistic about what is possible, and in which they no longer yearn to be transformed because they have made peace with who they actually are right now.

For us in our thirties and forties, this might be the easiest self-help advice we've ever received. No hot yoga contortions, or complicated positive thinking instructions or petulant inner primates. We don't even need to move to mid-Sussex.

All we really have to do to be truly happy, is to wait. It seems that the best really is yet to be.

Ruth's book The Pursuit of Happiness, and Why It's Making Us Anxious is published by Hutchinson and available for order on Amazon.