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Soon after I got engaged, a married friend told me about "the Penny Game." In this game, a newlywed couple puts a penny in a jar each time they have during the first year of . Then, starting the second year, the couple takes a penny out each time they have sex. Supposedly, the couple will never again have enough sex to empty the jar. This old wives' tale represents a commonly held belief that sexual desire declines over the course of a relationship. But is this true? And does it happen to everyone?

Sexual desire and sexual frequency do tend to decline over the course of a relationship. Several large-scale surveys have found evidence of this; one study even found that the link between sexual frequency and relationship duration was stronger than the link between sexual frequency and age (Johnson et al., 1994). So, young or old, sexual desire is likely to peak at the beginning of a new relationship and steadily decline from there.

But is that the end of the story? Once we enter into a long-term relationship, do we have to sit back and accept that our hottest days are behind us? According to recent research, not necessarily: There may be some steps you can take to help maintain your sexual desire over time.

One such step is thinking about the types of that you have for your relationship. When you think about what you want to get out of your relationship over the next couple of months, are you thinking about the fun you want to have with your partner and how you want to grow closer and develop a deeper relationship? If so, you have strong approach goals—goals focused on the pursuit of positive experiences in one’s relationship. It turns out that having these types of goals can help buffer people against declines in sexual desire in their relationships (Impett et al., 2008).

Specifically, people who have strong approach goals report having greater sexual desire in their relationships relative to people who have weak ones. Not only do they have more sexual desire to begin with, but they are able to maintain that level of desire over the course of six months, whereas people who have weak approach goals experience the more typical declines in sexual desire over time.

Why might approach goals be the magic elixir for maintaining sexual desire? One reason is that people who tend to focus on the rewards they can gain from being in their relationship (i.e., strong approach goals) also focus on the rewards they can gain from having sex. So strong approach goals for the relationship translate into strong approach goals for sex. People who are focused on the pursuit of positive experiences also report being more likely to want to have sex to have fun, grow closer to their partner, and make their partner happy. These sexual approach goals then translate into greater sexual desire. Who wouldn’t look forward to sex if they are thinking about how fun it is and how it makes them feel good about their relationship?

Another reason why approach goals might help people maintain sexual desire in their relationships is because people with strong approach goals seem to do a better job of weathering relationship pitfalls. Typically, when people experience a negative relationship event, such as having an argument or getting criticized by their partner, they experience less sexual desire relative to days without such negative events. Which, of course, makes sense: Who looks forward to having sex with a partner who just criticized them? Apparently, people with strong approach goals. They feel similarly high amounts of sexual desire regardless of whether or not they had a fight with their partner. They also are better able to make the most of the good in their relationship, experiencing boosts in sexual desire on days when they have a positive experience, such as doing something fun with their partner or receiving a compliment.

For those of you who are working on emptying your jar, perhaps it's best to focus on the positives in your relationship—that may be just the thing you need to jumpstart (and maintain) your spark.

Do you find that focusing on the positive in your relationship helps you want your partner more? Do you know of other factors that can help people maintain sexual desire over time? Do you know anyone who actually tried the Penny Jar Game?

Impett, E., Strachman, A., Finkel, E., & Gable, S. (2008). Maintaining sexual desire in intimate relationships: The importance of approach goals. Journal of and Social Psychology, 94 (5), 808-823 DOI: 10.1037/0022-3514.94.5.808