I feel this. Getting there myself. Part of the problem is that I can't experience sexual pleasure and I have a hard time experiencing sexual attraction. But I really wish I could experience what those endorphins feel like even once! But even doing it myself, it doesn't work that way.
To my knowledge, I don't seem to have any physical abnormalities. I've been to the doc for a checkup before there. Nerves just must not be hooked up right or something.