They say the climacteric hits at 42 years of age — six times seven. At seven years you leave your mother's side; after 14 you're physically capable of fathering a child; at 21 you're mentally capable of parenthood — just. At 28 you're seriously considering your future and at 35 you're living it. At 42 you're past the physical peak, and you might have your first grey hair. The Tour de France has been won by a 42-year-old, but as you look ahead to 49 you know that your dreams are behind you.

And that's when the midlife craziness can come upon you. You buy a Harley, get a hair transplant and start chatting up your son's girlfriends. You throw up everything and start a new business. To every looming obstacle you have but one reply: "I'll burn that bridge when I come to it!"

Rogue male territory

The revolution in your behaviour might even land you out in rogue male territory — permanently. Evolutionary psychology probably has an answer for this phenomenon, in terms of the much shorter lives enjoyed by our primate ancestors. When we exceed our design lifespan, our sell-by date, we tend to click back to 21 and try to live it again.

Or some of us do; a psychiatrist once told me that men only have midlife crises if there's something unresolved in their history.

An elite athlete may have a mid-life crisis in his early thirties, when he can no longer compete at top level. Expect trouble if he has no non-physical pursuits to fall back on.

But the climacteric is not inevitable. It seems that you can be too busy living to notice that you're getting old, especially if you're self-employed.

My lad, if you're pushing 40 and beginning to brood about all those life targets you haven't achieved, that's the first sign that you might be subconsciously planning to grow old disgracefully, like a guy I once heard about.

Trapped inside the body of Eddie Eksteen?

The said man called his wife and childen to a family council and solemnly announced that he was going off to start a new life — and that he was in love. After a moment of stunned silence, as they contemplated his bifocals, bald head and beer-boep, the entire family, including his wife, burst into laughter. It's not easy being Johnny Depp trapped inside the body of Eddie Eksteen.

It was the wife, a delectable divorcee of my acquaintance, who told me the story five years down the line. By then, her ex-husband's climacteric was over. His main hobby was TV watching, and love was out of the picture.

His one-time wife, ironically enough, had used the divorce as a springboard to an entirely new life and fulfilling career.

Women have mid-life crises too. They may try to take up painting, poetry, cycle racing — whatever they were planning to do before the rat race or the child-bearing years intervened.

They can be just as mad as the men, but tend to express their folly in more mature and practical ways. A lady in the throes of a mid-life crisis can be a delightful companion; a man in the grip of the climacteric usually has to be endured.

If you think you can see it coming, beware. By that stage you'll be in the crisis, head over heels, already saying — and doing — things that your friends try tactfully not to notice.

What good advice can I give you? None, my boytjie! You're on your own on this one. If all goes well, you'll come out the other side with the knowledge that thare's more to life than nubiles without cellulite. Careerwise, you might have discovered that envy can be corrosive.

Believe me, the guy with the career and the lady with the looks might envy your post-climacteric serenity in their more honest moments.

Tom Rymour is the author of the book 'Rogue Male: A survival guide for the newly single man'. Available from Two Dogs.

AFP