Dear Practo User. Thanks for sending across your query. Generally this is a common issue that arise in people. We generally call it as a Erectile Dysfunction. Due to lack of proper guidance and ignorance, this issue does not get resolved easily. It is appropriate to consider the varied options available for solving this issue, such as, counselling by a Sexologist, modern and alternative medicines, and non-medical methods like exercises/techniques of controlling erectile dysfunction. Healthy diet, regular workout, 8-9 hours of sleep, meditation etc., can also help you get rid of this problem. A size of 3-4 inches of penis is sufficient for giving pleasure to your partner. In case you have a "really small" penis, you can talk to us on for some Ayurvedic treatment.