"Do not deprive each other except by mutual consent and for a time, so that you may devote yourselves to prayer. Then come together again so that Satan will not tempt you because of your lack of self-control." NIV translation
The sexual relationship is good and proper in a marriage that is from God. As we see here, it is also a gift from God that protects us from attacks by Satan. Paul advises them (and us) that we are only to give up this gift for a short time so that we can focus on prayer and it is only to happen by mutual consent. Do you want to defeat adultery, pornography, and all the other tools of the devil in this area of your life? The simple answer is to be in a solid marriage.
"I wish that all men were as I am. But each man has his own gift from God; one has this gift, another has that." NIV translation
This verse has wrongly been taken to mean that Paul was never married but that is not what he was saying. At the time of this letter, Paul was evidently either a widow or his wife had abandoned him when he accepted Christ. He had been a member of the Sanhedrin (see Acts 26:10) and it was a requirement that, to be a member, you had to be married. According to the Mishna (oral traditions) a man was not a man if at the age of eighteen he did not have a wife. After his wife either died or left him, Paul remained single. What he was saying, here, is that his ability to focus on God and not be tempted by the desire for a woman (stay single) was in fact an ability (gift) given to him by God. He wishes that all men had this same gift but realized that God gives this gift as well as others to whom He chooses.
"Now to the unmarried and the widows I say: It is good for them to stay unmarried, as I am. But if they cannot control themselves, they should marry, for it is better to marry than to burn with passion." NIV translation
There have been many "church leaders" that have taken this passage wrong and then taught others that those who stay unmarried and live like monks are more godly than those who marry. They have even made up rules such as a priest could not be married. That is not what Paul is saying. He is simply asking those that are unmarried to pray and to really search themselves to see if God has given them the gift of being able to stay single without the devil creeping into their lives. If they have that gift, it is good as they can be single and not tempted in that area by Satan. If they do not have that gift, he is telling them to get married (and he is not telling them to marry just anyone) to close that gate of temptation by the devil.