Temperance is, or should be – as with all pleasures – an element of marital lovemaking. Sexual pleasure is a wonderful gift from God intended to stimulate and reinforce our movement toward and attachment to a great good: intimate union with our beloved (a union of many levels: physical, emotional, affective, intellectual and spiritual). And we want to keep something so beautiful rightly ordered.
We can’t be blind to the fact that sexual pleasure is so powerful that it can become an end in itself, instead of being a force that guides us to our good. That is what John Paul II meant by his controversial comments that it is possible for a husband to look at his wife with “lust.” He wasn’t criticizing sexual desire (about which he spoke beautifully in his book Love and Responsibility) – as he was commonly misunderstood. He was pointing out that a husband can be so focused on sexual pleasure that his wife can become a means to that end, rather than the other way around: the pleasure being a means to enhance his love of his wife.
This means that it is good to deny oneself sometimes, in order to establish and maintain control over the desire (instead of it controlling us). But this "denying ourselves" -- which looks so negative to some people -- is really something that frees us, and helps us to achieve the more comprehensive and fully human joy that comes from living marital chastity.
It is not usually necessary to go searching for opportunities to live temperance in marriage: the ordinary circumstances of daily life, and the different temperaments of the spouses will typically provide many opportunities for it. He wants to make love now, she doesn’t. He wants to give or receive pleasure in one way (e.g. oral foreplay), she prefers another. He wants the lights on tonight, she wants them off. He likes the evening, she likes the morning. (It’s actually a long list!) Just as we all have different tastes in matters of food or music or perfume, there are different preferences in lovemaking. Accepting a spouse's preferences with affection, and without whining (either inwardly or outwardly) -- the thoughtful "compromises" spouses make for each other -- are important forms of charity in marital lovemaking. They are a concrete reminder that sex is a means to an end, not the end itself. They are ways to live the virtue of temperance, which frees us from compulsions that undermine our efforts to achieve the joy of marriage.
And, of course, earlier in marriage, prior to menopause, there are opportunities to live temperance, if there are times when it would be best not to have another child, and the couple chooses to live periodic abstinence (natural family planning).
Those periods are a wonderful opportunity for a marriage, and especially for a husband (though, of course, most of us husbands don't FEEL that way!). It gives him a very concrete opportunity to show the control he has over his sexual desires, which makes it possible for him to give himself freely in the marital act. After all, if sex is a compulsion -- something he just "has to have" and that he can't "go without" even for short periods of time -- how can he say that he gives himself freely? When he comes to his wife, can he say "I freely bestow this gift of myself on you," rather than (if he were honest) "Honey, I just need it, so you're going to have to give it to me"?
And, of course, during that time of "doing without," rather than sulking or whining (a fairly common inclination among men when they have to forego marital sex), he can show his love by finding other, non-sexual ways to show his affection for his wife.