something that worked for me, i dont know if works for anyone else, when i was 16/17 i used to cum quickly, not like get in there and its done but the sex didnt exactly last long, all i did was for i dunno about a year, start quite slowly then build your way up to your previous speed and beyond, see my girlfriend enjoys long rough sex (shes a bit of a slut with few moral restraints ) before i started this thing it would be short rough sex, but now its alot longer because ive wiened (is that how u spell it) myself into gaining that much pleasure through the preferred sex. for me it was about self control.