Hi doc, I am 18, I regularly indulge in masturbation, I am trying my best to reduce, usually once a day but some days i do it 2-3 times..what worries me, Is that I do not let the sperm exit as i hold down hard on myself with my hand and do not let it out..I haven't given it much thought but now i am worried if it could cause some serious problems? please advice. Thank you..