Dear young man, Thanks for writing to HCM. I understand your concern regarding weak erection. I read that you attribute this to masturbation with back massage instrument. Masturbation in private or with a partner is generally considered a normal and healthy part of sexual enjoyment. Masturbation is not a disease hence no adverse effects. Masturbation itself does not cause impotency. It is a myth. The erectile problem in your case seems more due to worries and anxiety about inability to perform and also perceived effects of masturbation. Let me know whether you achieve and maintain a good quality of erection in sleep, in the early morning, during masturbation but not at the time of coitus? If you are able to achieve and maintain erection in any one of the above mentioned situations than your problem is more likely psychological rather than physical. So relax and just enjoy pleasurable sensation during masturbation. Do not focus on size and your performance during masturbation. Just enjoy kindling and loving with touch in the way both of you feel comfortable, rather than focusing about your performance and pressure to satisfy her. I hope this will be helpful to you. Best wishes for good sexual health.