I am not talking about having 'fun' or feeling happy on a day to day basis; but in terms of life being significant in retrospect.
From that perspective, life was significant until I had 'grown-up' - which seemed to finish about aged 21.
Then, in retrospect, I was filling-in time for more than a decade until I got married - and the longer this gap extended, the more obvious was the fact that nothing I did to amuse myself really mattered.
Of course, this was the time of all the 'action' in my life as far as the world outside was concerned, all the stuff that is supposed to be important - academic success, career progress, travel, high living...
It's just that - both at the time, and even more in retrospect - well, it amounts to a big effort at keeping myself distracted.
This is not an expression of regret - not a matter of saying that I wish I had done something different (because then I would not have married my wife, had my children) but that from experience it seems that people are meant to get married and start families in their early twenties or thereabouts.
That is real life - and all the lifestyle stuff is nothing, really.
And a society which apparently values that twentysomething/ thirtysomething stuff such that it is organized strategically to defer and defer marriage and families to make way for it, and self-propagandizes relentlessly in favour of lifestyle and against the real business of living - well, that is a sick society.