Personal experience and past event
Sharing personal experiences in a speech can enable your audience to identify and connect with you, but you need to organize those details so that they illustrate an argument. Like any other kind of speech, one drawing from personal experience should not ramble -- its conversational style still needs structure. Even if your speech needs only be introductory, it should still present a precise and pointed version of you or your views that is best demonstrated by a particular experience you had.