My FIC instructor asked me a good question:
What is more important to understand?
a) The principles of lift and drag
b) When your medical licence expires
Answer being 'b' because 'a' is irrelevant unless you're legal! Simple, see?
You will be teaching someone for a PPL, which is a recreational licence, so you need to become adept at simplifying information.
The course itself was the most enjoyable I've undertaken and I learned loads more about real flying than any of the other courses. It is tough in the sense that you might know how something works but as you shall discover, it's a different thing entirely knowing how to explain it in simple terms to a novice.
The good news is that you get better at doing it as time progresses! After about 100 hours as an instructor you'll start to relax more and enjoy observing how different people react to your teaching methods which must be adaptable to suit the many different people you shall be teaching.
It is a great job if you are a people watcher and good communicator. The fear of meeting, greeting and briefing students passes with time and it doesn't really matter if you're the shy type because this actually makes people less self-conscious, therefore more comfortable, which is what you should aim to do as an instructor from the off.
But know when to speak up and be firm!
VFE.