Absolutely not true. It's normal and healthy to masturbate.

Masturbation is not bad for you in any way. In fact, it is good for you! It has many health benefits including decreasing your chances of prostate cancer later in life.

These are old tales people used to tell their sons to stop them form masturbating. Why? All their dads, cousins, uncles and friends masturbated.
Masturbation is not BAD. Are you masturbating now? Does it feel good? Why would you want to stop? It is a personal matter for you to decide.
but it is not bad so don't feel guilty about it,

Masturbation is healthy and important for your prostrate health to prevent "clotting", due to disuse of the tubings.

Excessive masturbation, as all things overdone, are not good. Physically, they can cause swelling of your prostrate, etc (but that would have to be many many times per day or something depending on the person). Psychologically speaking, its only excessive if you find it difficult to do normal activities without masturbation affecting it (i.e. sex with your girlfriend, every time you try to study).

Masturbation is healthy, but is better if u stay with someone...

Dont Worry, if u want to masturbation, go ahead and be happy...

sid1, speaking from a medical point of view, masturbation has no negative effects but if considered from a moral perspective, it is completlely a different story. Having said so, anything done excess, generally, is not good. Some of the respondents are saying masturbation reduces chances of prostrate cancer and I won't challenge that but I would also make it very clear if you don't masturbate at all still it's not going to cause you any harm since when the sperm production has reached a very high level, it will be released in your wet dreams. Masturbation is not the only option to reduce chances of prostrate cancer, there are simply too many other options. I haven't hard of a single person nor a doctor saying that a person has got prostrate cancer simply because he did not masturbate. If our dads, cousins, uncles, and friends masturbate, as said by one of the respondent, we do not necessarily have to masturbate as well. In short you have to keep two things in mind

1) Excess of anything (in this case it's masturbation) is generally bad.
2) If masturbation goes against your moral thoughts, you can very well quit this habit and it will not cause you any harm. Personally, I do not like masturbation. Hope that helps.