So you didn't get it right the first time — "yes" tumbled out before you could think about it. There are still ways to back out gracefully, which is better than not backing out at all and being an unexplained no-show. Here are tips for getting it right the second time.

Correct your mistake sooner rather than later.

The longer someone has false hopes of your involvement, the harder it will be for her to replace you.

Admit you screwed up when you said yes.

Acknowledge any disappointment, but don't wallow in it. Just say, "I know this complicates things for you, and I apologize for that."

Don't feel obliged to elaborate on how or why you've come to your senses (unless it's a good friend).

The less you say, the better. Any excuse you give invites scrutiny and more discussion.

Offer to help find a solution or a person to take your place.

It's a nice thing to do, and the memory of this added chore should remind you to say no immediately to future requests.