The first session I had with a mistress I was relatively terrified, maybe even so much so that I couldn't fully appreciate it though I did enjoy the experience very much. About a week later I was traveling and went to a dungeon in another city, and had an almost out-of-body experience. Every thing she did, every word she uttered, every boundary she pushed - it was as if there wasn't anything else in the world but that moment and her. At the absolute height she blindfolded me and used sounds. I was petrified but released myself completely to her. It was such a rush to just trust that while she had pushed me beyond what i thought I could handle she knew that I could and I gave myself to her. And I've never forgotten her.
That's probably the only time I've ever gotten that far outside of myself, but I'd really love to get back there again some time.