There are a couple of ways....the easiest one is to tub some special numbing lotion that you can buy at an adult store, but it's not recommended for extended use. You can loose sensitivity on your member. The other one, would be to stop as soon as you feel like cuming, and start up again slowly. Do this for as long as you can and you'll start seeing the difference in time. There are "cock rings" that one can buy, but they also have to be used with caution. These rings help you maintain and erection longer but keeping blood in your member. Let us know about your results...... I'm not a doctor, but I don't think you have a medical problem.....It's quite common to suffer from premature ejaculation...especially as a young male.