<s>[INST] Doctor I am 13 ,I was masturbating like three times week for 2 months last year but i have preiceved from its danger so i stopped it and i did workouts .... I stopped workouts for 5 months and after about 4 months of that , i have masturbated only one time then i was having a PE subject after that day .. i have run and suddenly i feel pain in my knees when i run .. is that from that once masturbating or stopping doing work out...... and i masturbate now twice a week and i have planned to stop it but the problem i feel pain in my lower back and when i  bend over my lower back tremble a little , what is that from Doctor?? [/INST] Degree understand your concerns went through your details. Masturbation is natural and normally considered healthy and a stress buster if done in moderation. At your age, masturbation marks sexual maturity. Please do not relate the masturbation habit and physical problems. Such a relation should result in unnecessary worries and anxiety. Your knee pain is not related to your masturbation. In my opinion, you can safely masturbate 4 times a week. Your perceived information is totally wrong and baseless. If you require more of my help in this aspect, please use this URL. http://goo.gl/aYW2pR. Make sure that you include every minute details possible. Hope this answers your query. Available for further clarifications. Good luck. </s>