It's called "willpower". One can't give up breathing or pooping, but one can give up things he has control over. When you get up in the morning, you have a choice of putting on a pair of pants or a skirt. If you have the willpower to stop crossdressing, you will put on the pants and discard the skirt.
I'm not saying that anyone should give up crossdressing, only that they can if they really want to.





