A prenuptial agreement can do more than just spell out which spouse retains certain assets in case of a divorce. It also can be a useful way to spell out guidelines and expectations for behavior during the marriage.

These so-called “lifestyle clauses” can sometimes raise eyebrows—for example, provisions that a spouse remain under a certain weight often are considered inappropriate and demeaning. But in many cases, lifestyle clauses can encourage couples to explore concerns about important issues—beyond money—that are likely to arise over the course of a marriage.

Important: Some lifestyle clauses have been challenged in court—for example, whether an infidelity clause is enforceable—and rulings have been mixed. The rules vary widely from state to state. Your prenup should include a “severability clause” stating that if one or more of its clauses is invalidated by a court, the rest of the agreement, such as directions on the division of assets, still stands.

Most prenups come into play after a divorce has been initiated, but there has been a growing trend toward including clauses that define acceptable behavior within the marriage…and that mandate penalties—often token fines of a few hundred dollars—for violations. These penalties may not hold up in a court of law, and they may be merely symbolic for couples who have merged their finances, but they can be helpful in defining the parameters of what’s acceptable in the marriage.

Here are six ideas to consider for ­lifestyle clauses—and two to avoid—when drawing up your prenup…

Consider These Prenup Clauses

Avoiding intrusive in-laws. Dealing with family members is often a point of contention for married couples, such as when one spouse’s parents visit too often and/or stay too long. You can head off potential strain on your marriage by addressing the issue in your prenup. Your agreement may include a clause that limits in-law visits—for example, that in-laws can visit only once every six months and that the visits can last no more than two weeks. For in-laws living nearby, the clause may limit them to, say, two visits per week.

Incentivizing vacations. Your prenup can specify how often vacations should take place—such as at least once a year—and even how much money will be spent on them. These clauses make sense when one spouse is a workaholic and might need extra incentive to take time off. Some couples include a provision that shared assets can be used to pay only for family vacations—not, say, to pay for a trip that only one spouse takes with friends or to visit his/her ­extended family.

Discouraging (and defining) cheating. In many states, courts won’t financially penalize an unfaithful spouse when dividing assets in a ­divorce. But an infidelity clause in your prenup can impose a financial penalty on the spouse who transgresses—for example, by requiring the cheating spouse to pay all divorce-related legal fees. And while including an infidelity clause may not keep your spouse from cheating, it can provide an opportunity to discuss your values and feelings about fidelity before you get married, which may benefit your relationship down the road. If you find that you and your spouse-to-be disagree substantively about these issues, it’s better to know that now—even if that disagreement ends your relationship.

Caution: If you include an infidelity clause in your prenup, make sure that you define what “infidelity” (or “cheating”) means in the context of your marriage. Does it include only sexual relationships? Does sexting (sending sexually charged text messages) or e-mailing sex-related messages count as cheating? These discussions can further help clarify each spouse’s stance on fidelity in a relationship.

Ensuring quality time. A prenup can cap the amount of time that a husband or wife spends on hobbies or other activities that typically involve only one spouse.

Example: Your prenup may cap the amount of time one spouse spends playing golf or tennis or watching sports on TV to 10 hours per week.

An agreement also can specify that a couple spend a minimum amount of “quality time” together, defining “quality time” according to their shared interests and values.

Example: You could specify that the two of you will eat dinner together at least four times a week or partake of at least one shared cultural activity per month, such as going to the theater or visiting a museum. Such a mandate may seem controlling, but it’s one way that a busy couple with diverse interests can encourage themselves to spend time together.

Navigating social-media pitfalls. People live more and more of their lives online, which is one reason that ­social-media clauses are becoming an increasingly popular addition to prenuptial agreements—especially for people whose online reputations, either for professional or personal reasons, are very important to them. To retain control of how you are presented online, for example, you might specify in a prenup that your spouse needs your approval to post photos of you online…or that in the case of a divorce, your ex won’t post anything disparaging about you online.

Encouraging marriage counseling. While a marriage is meant to be a lifetime commitment, a prenup can strengthen that intent by also including a commitment to work on problems should they arise. To that end, you can include an agreement that you and your spouse will seek professional marriage counseling for at least a set period—say, three months or six sessions—before either of you initiates a divorce. This provision may help you avoid a split, and even if it doesn’t, sessions with a counselor might help you end your relationship in a more amicable and open way.

Avoid These Prenup Clauses

Setting divorce terms involving children. Courts regularly invalidate prenup clauses involving how children will be treated in the case of divorce—for example, agreements about the amount of child support a spouse must pay or guidelines for visitation rights in case of divorce. Don’t bother including such clauses in your prenup, as they likely will be overruled. Some prenups do, however, include what attorneys call a “no diaper” clause—specifying that the couple will not have children.

Setting sky-high penalties. Celebrity prenups have generated headlines for including million-dollar penalties for cheating, but that doesn’t mean that yours should attempt a similarly dramatic payout. In fact, if the terms spelled out in your prenup seem unreasonable, a judge is more likely to invalidate those clauses. There is no hard-and-fast rule regarding the right amount to seek, but courts are likely to reject penalties that are more than 10% of the annual income of the cheating spouse.