Then you're not doing it right.
It's like the old Croatian saying my father used to tell me*:
Ako ne želite biti otac, trebali biste se povući prije nego se počne osjećati dobro.
Ako osjećate zadovoljstvo, ona vas je uhvatila u zamku. Ali bez ikakvog zadovoljstva ti si slobodan čovjek.
(English: If you don't want to be a father, you should pull out before it starts to feel good.
If you feel pleasure, you're trapped. But if you quit before it starts to feel good, then you're a free man.)
* Some shit I just made up and translated in google translate, and then rephrased for the English translation.