An nice sidenote from the book that I am reading (listening actually) - A
short history of nearly everything - said that everytime you think about sex,
you release a tiny amount of testosterone. So, more you think of sex (watch
porn, wank, whatnot), the more you will want it (testosterone is the hormone
mainly responsible for male (and female too!) sex drive). So actually there is
a chemical reason why thinking about sex is obsessive.