Even negotiation instructors sometimes make negotiation mistakes. Since I recently made an exceedingly common mistake, perhaps it’s worth the public shaming that will necessarily come with sharing. At best, the story should make your own life more negotiable. At worst, it’ll offer me a form of catharsis.

Most of us tend to assume that we know ourselves completely—our every desire, need, and preference. It’s our wily counterparts—their needs, desires, and preferences—that we assume we don’t know and need to find out during a negotiation.

While we do know ourselves better than anyone else, I’m here to tell you that we don’t know ourselves well enough for a negotiation. Put differently, we can’t assume we don’t need to inquire into our own preferences carefully each time we negotiate. We always need to understand ourselves better.

To that point, my family recently decided to pay for a fairly involved and expensive landscaping project. Forever the negotiation professor, I tried to experiment with various methods of reducing the price. Voila! I could do so by performing a portion of the work myself. Sounds good, but the devil’s in the details—in this case, the work:  I would have to clear an exceedingly long, 20-foot wide strip of overgrown jungle that would challenge even the mightiest of bulldozers, pulling up fathoms of English ivy and removing decades of discarded yard waste.

“I’ll do it,” I foolishly declared, without asking myself whether my preference for savings outweighed my preference for health, happiness, and life satisfaction in general. And now, several days removed from an entire weekend of clearing, my back has never been so sore, I’ve never been so fearful of snakes, my finger is throbbing from a mischievous cinder-block, and I’m still drinking compensatory water. Oh, and I’m still sad that I had to miss my daughter’s T-ball game.

Now, was that really worth the savings? In retrospect, not really. Turns out that, although I do prefer savings to no savings, I don’t prefer savings to a totally lost, unproductive, and painful weekend of social isolation in the searing sauna of Maryland sun. In other words, I didn’t understand my own preferences particularly well—or if I did, I didn’t carefully compare them against each other.

I say this not just to poke fun at myself but because it’s a mistake that most of us make often. We assume, when negotiating, that we understand own preferences so well that we don’t need to consider them at all. I’m here to tell you that we always do.

So the next time you’re negotiating, don’t pull a Brian. I mean, do pull the Brians described in many of my posts, but don’t pull this one. Treat your own preferences as a question to be considered, a riddle to be solved, a topic rife for inquiry. Do that, and I think you’ll find your back less sore and your life more negotiable.