Thank you for asking. It is important to know that there not much variation in the sizes of penis within a given race. One should look to have better erections and learn an art of healthy sexual practice for obtaining more pleasure from Sex. Size of penis, time to ejaculation are not very important issues in sex, one should focus on correct techniques of seduction. Importance of foreplay, understanding the  physiological responses in sex, are important areas to know about. One should get his myth about sex clarified from expert. Faulty masturbation, pornography use are some important risk factors for sexual problems. I want you to consider on these.