Mastrubation is good or bad ?

Tough question. It's bad in the sense that it can turn your personality very selfish, and that is by no means a good trait. You may start tending to your needs all the time far too much, it becomes an addiction, you start to look at things that will in turn hurt other people for your own desires. It's quite animalistic, because all of the things you lose to it, you sacrifice for just a few moments of enjoyment. It's quite destructive. Try not to do it, it's certainly bad.