In short, your brain craves newness, and especially for women, your brain is very involved in your excitement and satisfaction. 'Anytime you introduce something fresh and novel into the bedroom, you set yourself up for a more stimulating experience and bigger finish,' says Vanessa Marin, a licensed sex therapist in L.A. Even the hottest spark in the bedroom needs new sex positions to stoke the flames from time to time-otherwise things get boring, fast. Your sexcapades, though? Definitely not one of them. Some things in life are better on repeat: Friends, perfectly sunny beach days, your trusty manicure.