If its because you find that there are so many to see, bruce, get picky man, get really really picky.
In your mind, complain about her boobs, her back fat, whatever it is that is just not right, droopy bum, ultra bad breath, whatever - too fat, to old, too wrinkly, too young and useless - just complain and list all these negative points of an mpa so much to yourself that shes just not attractive anymore. I guarantee this will reduce the number of MPAs that you even want to see.
If you are addicted to one or two specific ones, make them aware, perhaps they will do you a favor and turn you away sometimes.
Lastly, oneandten has a point, talk to a counsellor if you can.