Sometimes you have to respond publicly to an honor, an action, or an announcement. Often you do not have much time to prepare and your remarks may not be very astute and structured.
Recently I listened to the response of a woman who had just received a major award from the college. You could tell she was not used to speaking in front of an audience. When she came to the lectern, she tentatively looked over the audience of 100 and said, "If I had one iota of an idea that I would win this award I would have bought a new dress." The audience loved this response. She went on to say, "I come from a small town and I love that intimate and friendly atmosphere, so in my classes I want my students to feel like they have come from a small town, too." She then thanked the people responsible for the award and sat down.
I think she taught some valuable lessons in how to respond when you are surprised to do so. First, she took a moment to collect her thoughts. She did not start speaking until she had looked at the audience and paused. Second, she spoke from the heart. You could tell this was just an honest expression of her thoughts at this special time in her career. Third, she was brief. You may repeat yourself after two or three minutes or speak in vague generalities as you seek to say something meaningful. And finally, she tied her response directly to what required her to speak—the acceptance of this special award.
Others have followed this formula as well. For instance, Jane Wyman, accepting an Oscar in 1949 for playing a mute character in "Johnny Belinda" said, "I accept this very gratefully for keeping my mouth shut for once. I think I'll do it again." And she sat down.