Hmmm...
What on earth are you doing with your naughty thoughts and sexual fantasies?
There's no use pretending you're one of those practical women with no imagination, because you're not. Aren't you just being a wee bit lazy? You need to feed your sexual imagination, just as you'd feed your imagination in general - by reading books, watching films, talking to others and opening up your mind to new concepts.
Make a bit of effort and you'll soon see a vast improvement in your sex life. As long as you're not afraid to try out new things and take risks, you can't lose! It might be reassuring to stick with the same old routine, but you miss out on so much fun...