Excerpted from How to Turn Your Words Into Money

It was bad enough that I thought throwing a dirt clod at Kevin would be fun. But I made it worse. A group of us were throwing rocks down a hillside, aiming at a rusty barrel at the bottom. It made a satisfying clang when you hit it. Good, clean fun. But you know how things can go with boys throwing rocks.

I hurled my rock at Kevin’s head. I expected it to burst into a cloud of grit and dust. Instead, it hit him with a hollow thud—a loud sound I can still hear. Kevin toppled over like a tree. Then lay there motionless, blood trickling from above his ear. Half of the kids scattered, yelling. The rest clustered around Kevin. I stood outside the circle, unable to move.

“Dude, you killed him,” someone whispered. I knew the awful truth. I had murdered my friend.

Then, a miracle. Kevin sat up. He shook himself, said a four-letter word, and flung a handful of loose dirt at me. Within minutes, he and the others were throwing rocks again.

I didn’t recover as quickly. I went behind a tree and vomited. Then walked home on rubbery legs, replaying the scene over and over in my mind, hearing the sound of the rock thunking against his head, seeing him fall.

I still cringe when I think of that day. It changed my life. It made me more careful, less apt to follow an impulse. Even now, if I pick up a rock to throw it, a knot forms in my stomach. I falter. Double-check to make sure there’s nobody close by.

Guilt is one of the strongest motivators in human experience, as I discuss more fully in my new book, How to Turn Your Words Into Money. You’ve no doubt felt its power, too. But as powerful as it is, guilt is a risky tool for fundraising. There’s almost no way to invoke it without creating a backlash that’ll put you at odds with donors and cause you to miss the mark.

In fundraising, there are three types of guilt that sometimes show up. Each has its own dangers. Only one is even marginally helpful for motivating donors.

Direct Guilt: The Accusation

You haven’t done your part to solve the problem.

Some churches used to say this, but you rarely hear it any more. And that’s a good thing, because it’s toxic. The main problem is that accusing someone—even someone who fully deserves it—is more likely to make them feel defensive than guilty. The moment they sense an attempt to stir up guilt, they build barriers that destroy the possibility of compassion.

Anyway, a direct accusation in fundraising is misplaced. Donors and prospects aren’t the ones who should feel guilty. They’re the ones who are involved and doing the right thing.

Indirect Guilt: It’s Society’s Fault

Only one in a hundred Americans cares enough about the tragedy in Syria to give even a small donation to ease the suffering!

It’s tempting to say something like this, because it seems true. You may think it invokes a type of exclusivity, telling the reader she’s one of the special ones. The problem is when you tell donors nobody is giving, you’re creating social proof thatnot giving is the norm.

People do what other people do. If you make it clear that others don’t give, your message is Don’t give. You’d be better off telling your donors, Everyone is giving.

Implied Guilt: Look at Your Priorities

For the price of your morning latte, you can save a life.

This is a healthier form of guilt. It’s closer to the feeling charitable people actually experience. Donors look at the blessings in their lives. Compared to the needs of others, they can see that giving is clearly the right thing to do.

In fundraising I almost always advocate being direct. But here’s a place where indirect communication works better. To my knowledge, this is the only dependable way for fundraisers to harness the power of guilt. You harness it by not harnessing it.

The truth is some of the gifts you receive are atonement. Careless rock throwing in the distant past and other forms of personal guilt are no doubt part of the motivations of many donors. The only way to tap into these powerful motivations is to let the donor do the tapping. Other than that, guilt is a terrible fundraising tool you should avoid.