It also implies that for the last four decades you've been rather careless in completely wasting time and making very little headway or achieving very little in the way of success. Apparently though, this stock phrase offering is supposed to make you feel better.
Being 40 today is quite different to when our parents or grandparents turned forty. 40 is still young, and it's more a case of being allowed, or allowing yourself, to try something new. At 40 you've very likely got into something of a routine, determined what you do and do not like, what makes you tick, and you may be thinking about things you have always wished you had done, but hadn't ever quite got round to organising. At 40 you generally still have your health, you may well have a little spare cash to enjoy, and you're probably reasonably secure in who you are and what you want to do. So in a way, you can treat your 40th like an excuse to indulge yourself, or allow yourself to be indulged by others. Head off for an adventure, visit someplace you've never been to, do something you always imagined you'd have got round to doing if you had a parallel life. Be a child again, but with all the benefits of being grown up.
Of course, for anyone charged with the task of organising a 40th birthday party it can be a little unnerving. Do you make a huge song and dance about the Big Four Oh, or do you keep it down? That depends on the person whose birthday it is, and how they're coping with the news. If they're joking and laughing at themselves getting old, then make a huge thing about it. If they're quietly curling up in a foetal position and spending an hour or two sobbing, it might be kinder to keep the number subtle. Remember, 40 is simply 39 and a few months. Mind you, it's also 21 and a few months.
But who counts months once you've emerged from your teens? If you, or someone you know, is turning 40 this year, then there's good company to be had. Other well known people who are turning forty during 2013 include Jude Law, Eminem, Vanessa Paradis, Ben Affleck, Gwyneth Paltrow and Cameron Diaz. Not such a bad bunch of people. Although I wouldn't advise looking carefully at how they all look before peering in the mirror. After you've counted your chins, and then double checked to be sure, cleaned the lint from out underneath your eyebags, taken the sheers to your ear hair (hopefully just the men) and slapped some Polyfilla in the larger wrinkles, you may come to the gloomy conclusion that if looking 40 is looking like Hollywood celebrities, you look about 85. Never mind, another ten years and you can look forward to a nice quiet holiday courtesy of Saga.