Remember that your body which you work hard to fulfill it's instincts will be rendered to dirt after death , live for your after life , Chastity and purity is to deny your body's lust and instincts and to pay attention to your afterlife .
Your body lust is not a shame and its not your fault. It is a need. So the first step do not be shy of your lust, recognise it and then control it. Avoid situations and locations that drag you out of control, this second, and thirdly pray for help whatever you are hindu muslim christain or jew.