dear user, thank you for contacting HCM for your health related query . regarding your complaint of premature ejaculation , first you have to relax as your lean built and masturbating habit is not contributory in your problem . There is no scientific research that has proven that lean built people or person who masturbate perform poor in sex. Also sex is a act of senses as well - so it is likely that when you perform sex with your partner with a lot of foreplay , you will enjoy it more . you can also choose to visit a psychiatrist who can tell you some sex techniques like squeeze and stop technique , to help you last long ....medicines are not usually the first mode of treatment here but yes some medicines like SSRI s (selective serotonin reuptake inhibitors) like paroxetine can delay the ejaculation time , but they need to be prescribed by a psychiatrist after due evaluation. Hope i answered your query - if satisfied please rate the answer - any followup queries are welcome . Thank you