It is a privilege to be a FI!
But the price of safety is eternal vigilence. Obviously it is a bit nerve racking when you first start out but you can soon learn enough to relax and enjoy it! Flight instructing has the best safety record of any type of GA flying. Of course FIs love to talk about how terrifying it is -but it is just talk. Go forth with confidence (just be very, very careful!!)
Plus it is amazing how your skills improve just from observing and having to put concepts into words.
Never forget what it was like for you when you were learning. I miss instructing now and look forward to maybe one day becoming a training captain.