Begin the speech with an introduction. This will set the speed and the tone for the rest of the speech. Use past tense and first person. Imagine this portion like the beginning of a story. A way to start may be, "I didn't know what to expect when..." or, "There was a time..." or, "I never knew... ." This will let the listeners know that your story will be progressive.
Make notes of the most important events that led up to your life-changing event. If a person said something to you, that made you think, note it. If you were out getting a cup of coffee when you met your future husband or wife, note that you were out getting coffee.
Use the notes as your transitions. If a person said, "It's never as hard as it looks," then start a paragraph with that quote. "It's never as hard as it looks," pastor John said.
Write for slower-reading when reaching more emotional parts of your speech. When writing a speech, write the script differently from an essay you would turn in. Long pauses can be portrayed using ellipses. For example, "I never knew ... that that would be the last time I ever saw him alive again ... ." You don't want to exploit your own story, but slowing and adding pauses at the "hard-hitting" emotional parts will capture the audience's attention.
Place yourself into the important parts of your story. Allow yourself to feel as though you are experiencing the event again. The emotions you felt might come out in your voice, making the speech even more meaningful.
Reflect on the experience in your conclusion. Tell what your life has been like since, and how you will live your life in the future.
End your speech hopefully. Whether the experience was tragic or pleasant, your audience likely doesn't want to hear a sad story.
When ex South African president Nelson Mandela spoke of the changes he underwent while he was in jail for 3 decades, he survived by a poem called "Invictus." The end of the poem reads,
"It matters not how strait the gate,
How charged with punishments the scroll.
I am the master of my fate:
I am the captain of my soul"
If you are speaking about a terrible experience that happened to you and you survived it by the words of someone else, it might be beneficial to end your speech with an empowering phrase similar to "I am the captain of my soul."