By not exercising them you will make them flabby...combine them with lightweight exercises and cardio..
There is a huge difference between "going to gym" and bodybuilding,so don't be afraid...eat well and clean,mix strength trainings with lot of cardio and you will get what you want... :)
You shouldn't worry to much about that sort of thing especially if you're just starting and letting that make you feel like not going. Many women worry about this but its unnecessary.
A woman has to work extra hard to bulk up and its not gonna just happen overnight. If you just workout and get your body moving and do some weight lifting you'll see improvements and nothing is going to suddenly hulk you into a monster.
Once you even get remotely close to this happening you'll be way more in touch with your body and how it reacts to the workouts. You'll have a clearer idea of what you want and how to get it.