I was tortured by it. Perhaps some people feel it is unhealthy for them, but they do not have the right to judge whether it could be healthy for others. If a human cannot satisfy their sexual craving they become frustrated, resentful, bitter, maybe even psychotic. Declaring masturbation a sin, can lead to severe sexual dysfunction and repression, because sexual craving is so over powerful and intense, and if it has no outlet, it can be dangerously destructive. Christianity condemns masturbation as a sin, and in so doing, it forces its followers to wrestle painfully with their sexuality.
Few teenagers can abstain from masturbation, because sexual craving is so intense at that age.
Those that do abstain often become incredibly repressed, those that fail to abstain suffer from painful guilt and still usually become painfully repressed. I was an example of the latter. Yet, regardless of the outcome of the battle with sexuality as a teen, the Church does have a method for channeling and satisfying the human need of sex. It has marriage. In marriage, sexuality is praised and celebrated as a blessed gift of God.