I would compare the anxiety to when I've jumped out of planes (not the sanest thing in the world). In the beginning before I gained confidence in my skills and equipement if I looked down prior to leaving the door it was HARD!! So I would either follow the person in front of me or watch the horizon. Also, don't think about the drop prior to stepping off. Concentrate on your equipment, skills, what you are supposed to do when you first enter the water, what to do when descending and enter the water. This not only makes these become second nature allowing you to become a safer diver, it also improves your skills and confidence. And, by the time you look around you're at 40' again. These are just different ideas from what your instructor did.