At dinner the other night with 50 partners in a corporate law firm, I looked around the room and noticed something alarming. I was one of the oldest people in it.

Where were all the lawyers in their late fifties and early sixties? I put the question to the man sitting next to me, who said they had mostly been eased out. The trouble with the law, he explained, is that it takes its toll on you, and if you’ve been at it for 30 years it is almost impossible to hold on to any sense of urgency. By the time you reach your mid-fifties, it is usually time to start thinking about going.

There was only one exception to this rule, he went on, and that was lawyers in their fifties who had recently been divorced and were starting again with mortgages and young children. They had all the experience of their years – and all the drive of someone 30 years younger. They were propelled by the need to make a vast amount of money but, instead of having a lifetime in which to do it, they had a mere decade. The combination of extreme wisdom and extreme hunger made them unbeatable.

I don’t think the man realised quite how well this divorce-is-great-for-your-career argument was going down with me. In the past six months I have a) separated from my husband, b) bought a wildly expensive house, and c) been feeling more than usually keen at work.

Until that minute it hadn’t occurred to me that the three things were connected, but then I saw what was perfectly obvious: a) and b) have caused c).

Sluggish

Everyone will tell you that divorce is ruinous to a career. It makes you so unhinged that you can’t think straight. A couple of years ago the hedge fund boss Paul Tudor Jones told a conference that as soon as he hears that any of his managers is going through a divorce he stops them trading. The emotional turmoil renders them too unpredictable to be trusted with anyone else’s money.

That may be so. But then again, it may not be. People, marriages and divorces come in many varieties, yet all divorces have one thing in common – they make you poor. Or at least they make you poorer than you were before. To comfortable, middle-aged professionals, feeling a little short of funds can be an unwelcome shock, and the effect of it can, in the right circumstances, be agreeably galvanising.

The main reason those in their fifties become sluggish is that neither money nor status move them as they used to.

For me, it has meant that any thought of sloping gently towards retirement is out of the window. And because there is to be no such sloping, I can no longer allow myself the luxury of mild disillusionment. Instead, I am applying myself to the job, and, to my amazement and delight, find that instead of feeling trapped or sorry for myself, I’m rather enjoying it. The work itself has not changed a bit, but I am doing it with more conviction.

This may not alter the quality of the finished product, but it does affect how it feels to be making it. Every time I am offered an additional piece of paid work, I no longer think: I’m not sure I can be bothered; I think: let me at it.

I am not saying that everyone in their sixth decade should ditch their spouse to give their flagging careers a bit more oomph. Neither am I suggesting that everyone who gets divorced can look forward to this kind of professional dividend. Some people are so poleaxed by the misery of it all that they can hardly crawl into the office, let alone feel relatively gung ho once they get there.

Feeling stale

Instead, what this proves is that the link between boredom, money and motivation is not what I thought it was. I used to think it was obvious why people in their fifties felt stale – it was because 30 years was simply too long to be doing the same thing.

I now discover it is more complicated than that. People in professional jobs work for three reasons: money, status and the interest of the work itself. The main reason those in their fifties become sluggish is not that their minds are going, nor that the work itself has become too monotonous. It is that neither money nor status move them as they used to and the interest of the job is not enough to keep them going on its own.

You would have to be a most peculiar person to be prepared to stay up all night doing the legal slog on an M&A deal for the sheer fun of it. And even though journalism is arguably more enjoyable than corporate law, it is not so fabulously entertaining that I would consider doing it if I didn’t have to.

Almost all the scientific studies will tell you that money doesn’t motivate. Yet when you have just parted company with your nest egg and lost some of the financial security you thought you had, every pay cheque becomes a minor cause of celebration – and the same old, same old work suddenly seems as fresh and full of possibility as it ever did.