Sex is one of the greatest gifts God gives a married couple.  Sex is great.  Sex is also a place where our spouse needs our service.  Your spouse is totally dependent on your Christ likeness.  If one person is sexually self-centered, this can create pain for the marriage.

You can serve your spouse sexually first by guarding your sexuality, including your forms of entertainment, conversations with others, and what you view on the Internet.  Your sex organ belongs to God (Romans 17:1) and to your spouse (I Corinthians 7:6) not to yourself.