First of all - there is no harm at all in Mastrebation (unless you use it as a total substitute for participative sex. Then you may have a problem.
You can not harm yourslef with masterbation. In fcat in Australia a health study was carried out and found that amongst a survey of 10,000 men those who masterbated regularly (i.e several times a week) they had the lowest incidence of testicular and prostate cancer. No one is saying it is a cure but it seems beneficial.
I am 58 years old and masterbate at least 4 times a week and have sex with my lady 2 - 3 times a week.
Masterbation is pleasurable - so why stop. Enjoy it and keep on the look-out for love and a partner!!!