Like need for food is a primary goal of human. Sex also comes in primary needs.
Desire for sex is so powerful that it is not possible for a common people to avoid it. One who masters over his sexual need, He automaticaly masters himself. Think of our body as a chariot and our senses as its horses. Mind is the driver of this chariot and our soul is its master.
Mind is like a child. It goes in the direction of whatever senses ask for it. If it sees a sexy woman and she is calling. The charoit goes in that direction unless orders are given by its master The soul.
A Man who has complete control over his mind, body & senses doesnt fall in for pleasures like sex or tasty food. He doesnt even need for sex and tasty food to feel good because he remains all time high and doesnt needs any drug to feel happy. He is a contented man and always happy & motivated.