Once upon a time, managers were likely to stay with the same company from cradle to grave, as the idiom had it. Not today. Many managers now change jobs as frequently as they change their cars - or even their spouses.
In Japan, company loyalty used to be revered, but even there companies have now started to fire employees, and employees have hit back by becoming far more job promiscuous than would have been acceptable a few years ago.
So you can safely bet your P45 to an inscribed gold watch that you won't stay with the same employer throughout your career. Quite probably you have already changed jobs a couple of times - and will do so several times more before you mumble those few final farewell words at your last-ever leaving party.
Job switches being part of normal business life, you must learn to handle them as smoothly and effectively as possible. The first question to ask yourself is: when should you decide to quit a job?
Job-switching may be commonplace, but you shouldn't do it too often.
That may sound like a contradiction in terms. It isn't. If you keep chopping and changing, prospective employers will suspect you are unstable and cannot buckle down for the long term.
From your own point of view, it will mean you never learn to grapple with the disciplines involved in tackling lengthy projects and seeing them through. A rolling stone, as they say, gathers no moss. So you need to be very sure you are doing the right thing before you up sticks and move on.
Feeling disenchanted with your present position is not nearly a good enough reason to throw in the towel. We all get cheesed off with our jobs from time to time. We get furious with our bosses, with unhelpful and pushy colleagues, or with company policy, and feel an almost irresistible urge to jump ship.
It's inevitable. But it probably won't cure any of those problems for long.
Everywhere you go you'll find bad bosses, horrid colleagues and company policies you think are crazy. Before quitting, you must be quite sure your circumstances are irremediably bad and will not improve in the foreseeable future. Don't rush at it. Switch jobs in haste and you'll repent at leisure.
Don't set yourself unnecessary deadlines. I once decided I had to leave a particular job within 12 months - it seemed a long time when I made the decision - and I ended up moving to the worst job I have ever had.
Once you've decided to go, you must obviously pursue new openings energetically - but keep your options open. Under no circumstances should you take your foot off the accelerator at your existing job, as many dimwits do. Things may suddenly improve and you may want to stay. In any event, you don't want to be dismissed.
Nor do you want your employer to give you a lousy reference. However disagreeable it becomes, you must keep working your damned hardest until 60 seconds before you finally walk out the door (or even a few seconds later).
If deciding when to leave old jobs is hard, evaluating new ones is still harder. Some things are plumb obvious: you will want more money, more responsibility, better prospects. But the less tangible aspects of any job are more difficult to assess. The crucial rule is not to get too excited about, or committed to, any prospective job too early in the process. Winning a desirable job is like the unfolding of a love affair. If you get committed too soon you may well end up disappointed, when the job (or the love affair) fails to materialise. Worse, in your eagerness you will overlook negatives and be blind to drawbacks that - had you been more objective and analytic - would have been obvious.
Naturally, you must look enthusiastic to the prospective employer. But (again as in matters of the heart) while being enthusiastic as hell you must also keep your cool.
When you eventually make the switch, think carefully about how to handle your first weeks in your new habitat. Launching yourself in a new job is a bit like launching a new product: you don't get a second chance.
First impressions last for ever, so take things steadily: only fools rush in.
Don't be frightened to ask basic questions. Get people to give you every scrap of relevant information, and keep asking and asking until you are sure you have it all. Be polite but adamant. Do much more listening than talking.
Strive to have creative new ideas, but don't blurt them out: check them out cautiously, without letting others know what's in your mind until you are ready to go public. Don't get involved with any 'political' faction. Take a while to make friends.
Above all, forge a cautious but positive relationship with your new boss.
He or she will have been involved in recruiting you and will truly want you to succeed. Don't be bumptious, don't be cocky, but work like hell - and you'll be off to a flying start.
Winston Fletcher is FCB Europe's communications director.