There are two kinds of treadmills.

The visible kind is usually found in gyms (and the dark recesses of your home, gathering dust.)

After turning it on, you put one foot ahead of the other and walk. And walk. And walk. You can literally walk for an entire day, and yet you’ll be in the exact same place as when you started.

It seems like an enormous waste of time. Except that the more time you spend on the treadmill, the more calories you burn and the more weight you can lose.

This treadmill comes with a reward.

The invisible treadmill focuses not on walking, but on things. It promises you that if you just had one more thing, you’d be happy. And so you begin to accumulate. A shiny new phone. A nicer car. A roomier home in a better neighborhood. A more exotic vacation. A more fashionable pair of shoes. A bigger stock portfolio. A more prestigious award.

This type of treadmill, in contrast with the visible kind, feels a lot more like running and promises to lead you to a whole new place. But sadly, no. You have more stuff, but you’re still in the exact same spot, still looking for one more thing.

Not much of a reward.

As Charles Handy wrote in his book, The Elephant and the Flea, “Life becomes a long-distance race you cannot afford to quit, but also one that you can never win, because there is always someone ahead, always more to get.”

Beware the invisible treadmill.