Just one note to you all. Sexual performance is as much a spiritual thing as it is a physiological one. I see that some of you are pushing certain philosophies (Tao) and linking them to medical issues, i.e. erection and sexual function. I don't think that's accurate.
The guys that have started this topic obviously have psychological anxieties, rather than physical problems.
I myself have had periods when I felt depressed and down, and just could not perform sexually, even if I really wanted to. I find these phases to be normal. Sexual desire is the thing I find most important in erection, and other parts of sexual performance, i.e. length of intercourse, and overall level of satisfaction, not the actual physical properties of your organs, even though they of course matter.
What I'm trying to say is that you should relax, I don't think most of you are "over-masturbating", you just need to "chill"

. Looking at it physically, there is not much difference between masturbation and actual intercourse. The difference if of course larger psychologically. You need to be psychologically confident in yourself and be aroused with the partner you are having sex with, and the satisfaction and performance will come on their own, unless of course there is an actual physical dysfunction, which is a much rarer case and may be treated.
For the majority of us, it is the libido that drives us, which is purely a spiritual thing.
I'll give you an example: one evening I did not feel like having sex with my girlfriend, I kind of felt I'm getting bored with having sex with her. Then I accidentally ran into a girl from the neighborhood I used to like a lot, we had a short chat and I thought "she still looks amazing, boy, would I like to have sex with her", or something like that

.
Later, when my girlfriend came, I felt quite aroused and we had great, vigorous sex. Because my libido was awaken and I didn't feel like I was in a grunt. 'Physically' I was all right either way, it's the psyche that made all the difference. Had I not gotten aroused by that other girl, I'm sure I wouldn't have had sex that evening. Catch a drift?