Almost everybody, no matter how smart, ambitious, energetic, etc., grows tired of his or her job at some point. Usually, the feeling passes after a while. Sometimes, it lingers. It’s not much fun to work when you lack passion — and in case you are in any doubt, it’s not much fun for those around you. Ennui shows. It shows in your face, in the way you sit at your desk, and the way you walk into a meeting.

When your body language says, “I don’t love this anymore,” the rest of the world knows it. The danger is not in missing the fun or in risking public exposure, but in the infectious way ennui can debilitate a group. Like the common cold, it won’t infect everyone, but three out of four people around you will eventually get the bug unless you stop it.

You can stop it by doing any or all of the following:

* taking a short vacation

* reading a pile of inspirational books

* figuring out the biggest thing you hate about work and fixing it

If that fails, fake it. At least act as if you have passion. Screw up your courage and put on a game face. Sit up straight. Talk forcefully. Keep going like that and before long you may discover that you really do feel better.

MARKETING TIP: REINVENT YOUR PRODUCT — EVEN IF IT’S STILL GOOD

The most reliably profitable businesses are often those that sell products or services that need to be replenished. (Think groceries. Think magazine subscriptions. Think lawn maintenance.) If you are selling such a product or service, so much the better. But if you are not — if you are selling a “one-shot deal” — consider how you can make it replenishable. There’s always a way to make a perfectly good product obsolete.

Sometimes you can do so merely by making a few superficial changes (think Japanese cars). Keep in mind that most people tire of the same old things, even if the same old things are perfectly good. By taking an existing product and making it “new and improved,” you satisfy the customer’s desire for something different and give yourself a chance of reselling to your existing customer base — always a very lucrative practice.