Masturbation is no different than intercourse, only safer and more convenient. There’s no effect on your body that would be any different than intercourse.

There’s no such thing as “too much.” If you do it too many times in a row, your penis gets too tender to touch and you run out of testosterone until you have time to replace it, and you just don’t feel like doing it anymore for a while.

The only possible downside (other than if you use too much friction and get a friction burn), is that generally, guys try to be time efficient with their masturbation, and get it over with as quickly as possible.
This conditions you to come too quickly to please a woman, once you start actually having sex.
So, what guys should do, is take their time, try to drag it out as long as possible, stopping when they are close to coming until the pleasure fades a bit, start again, etc.

There’s certainly no physical harm masturbating though.
In fact, it’s good for you to get rid of excess sperm, and it exercises the prostate gland, which can help keep you from getting prostate cancer later on in life.

Calloused hands and blistered dick……and really over developed biceps on which ever arm you use ?

hairy palms!!!