It might seem like common sense that if you have great chemistry with someone, you'll have great sex with them too. But a series of studies published in the Journal of Personality and Social Psychology suggests that good sex actually takes work — and believing it doesn't can hurt couples in and outside the bedroom. University of Toronto researchers surveyed 1,900 people on their beliefs about what makes for a fulfilling sex life. The more people believed that great sex required practice, the happier they and their partners were with their sex lives and relationships. Those who believed, on the other hand, that sparks will automatically fly when you hop into bed with someone you like were more likely to feel their own sex lives were lacking. People with this belief, which the authors dubbed "sexual destiny," were also more likely to see their relationships suffer when they and their partners had conflicting sexual desires. "People who believe in sexual destiny are using their sex life as a barometer for how well their relationship is doing, and they believe problems in the bedroom equal problems in the relationship as a whole," lead author Jessica Maxwell said in a press release. "Whereas people who believe in sexual growth not only believe they can work on their sexual problems, but they are not letting it affect their relationship satisfaction." While having an instant connection with someone is great, Maxwell says this usually only sustains couples during the first two to three years of their relationships. Then, they have to put in the hard work of communicating what they want, exploring their fantasies, and putting aside time for each other. The good news, though, is that when couples do make an effort, this study suggests it pays off.