Conclusion

As you can see, you will not be able to slap together an effective, conclusive personal testimony on the fly. You will need to apply yourself diligently to develop your own. Once you have developed your testimony, and gained experience with sharing it, you will find that you are more relaxed and willing to share it. You will also be able to tweak it slightly, depending on the specific circumstances surrounding the opportunity to share it. Fear not, the Divine Presence is always there to guide you, and present opportunities to you, if you will only say to Him, "Hineni" (Here I am. I am available. Send me.).