I have memories of suddenly "falling," where all my muscles simultaneously go limp. It was the freakiest thing, and I tensed up.

You're a lot farther than I am. Congrats! Just try to remember that it can't hurt you. Instead of simply "feeling" it, analyze it. Instead of thinking of it as falling or some other sensation, simply say to yourself, "what an interesting sensation. It's simply astounding." Think of it as a sensation...it helps me, anyway. It also helps to diminish the pain inflicted by killer chili peppers.