Medicine or drugs could help, though.
I can remember myself being drunked as hell
while fucking a really awesome teen and I just
couldn't came, no matter how hard I tried. She
came about 8 times and I was starting to get
pretty tired. At least, I came, though. But it
wasn't realy a good orgasm.
So maybe alcohol could help as well.
Also, if you feel close to come and don't really
want it...think about something what really
turns you off like an old, phat, uglyass bitch
or maybe you think about work or somthin.